It should be fairly simple to make a lot unfurnished by setting the Remove Furniture flag in U0 in the LotDescription:
http://simswiki.info/wiki.php?title=DESC
http://simswiki.info/wiki.php?title=LOT

Reference: http://www.modthesims.info/showthread.php?t=501935

The obvious place for this is in the Clean Installer, but that program doesn't currently have the code required to allow modifications of the records inside of any package; all of the modifications are done at the package level (add / remove / choose where to install).

Still, I've verified that the change to U0 in the LOT record works well. This won't be as simple a change as I originally hoped, but it still seems doable.

Kind of along the same lines, but have you perhaps figured out how to remove linked custom terrain paints from a lot? As I'm sure you know, cc terrains that are included will flash blue after lot installation if the downloader does not have the terrain paint. And it seems almost impossible to erase them to clean the lot.

I have added a checkbox to the Clean Installer to remove furnishings from a lot as it is installed from a Sims2Pack. I have tested this on my computer, but I would really appreciate if a few people would test this before I give it out to everyone.

Please if you decide to try this, let me know which EPs and SPs you have installed and whether things worked as expected. If there is any problem with removing the furnishings, please include a download link for the lot.

Thank you to everyone who tests this and gives feedback.

[Update:] Removed. Obsolete. New version available later in the thread.

Have you been reading my posts in the "hacks you want" thread? I'll happily try this out.

I linked to the discussion thread that convinced me that this was possible, but couldn't find your post in the "hacks that I want" thread. I'd be very happy to have you test it for me. Please be sure to test in a temporary neighborhood first, just in case.

I downloaded this residential lot and this apartment lot and installed them into my game using the version of Clean Installer that you attached to post #4, setting it to remove furnishings.

When I entered the lots in game (in Buy/Build mode, with no residents living there) there were no furnishings from Buy Mode anywhere on the lot but all build mode objects (like air conditioning pipes, pool ladders, garden plants/trees etc) were still there.

I didn't encounter any problems using it and it didn't do anything I wasn't expecting :-) I have all EP's and SP's installed - double deluxe, and all the other EP's and SP's separately. I didn't test it in a CC-free game because it's late and I need to go to bed soon! :-) But, like I said, it seems to have worked correctly for this rather limited test.

It's a great idea and I'm looking forward to using it when downloading lots I actually plan to use in my game! I generally get rid of all the furnishings anyway, so this will be very useful to me :-)

Thank you very much. That's helpful because it tells me that the installation has the correct new DLLs.

Unfortunately, I have found one "bug". Fireplaces are removed from the lot along with all of the furniture. Note that this is an EA bug, not mine, but it's still annoying.

I just downloaded it, and will give it a whirl, Moo. I'll let you know what happens later, when I fire up my game...

Thanks so much for looking into this possibility and for making this. I'm guessing it'll work just fine because you're awesome, and if it does...Well, I'll be a very happy camper and will likely download more lots. Which will be useful to me because it's kind of hard to build stuff on this wee screen I have...

ETA:
OK, so I decided to give it a whirl while I ate dinner.

This was my victim lot. I installed the lot de-furnished, loaded the game, put it in debug mode, and placed the lot in the Neighborhood of Testing Weird Shit on the user account on my comp that has, currently, no CC in it, although it has had stuff on and off before, for the purposes of...Well, testing weird shit. I have all EPs/SPs, and in the install on this machine, it's all separate bits, no Deluxe, Double Deluxe, or any of the collection packs.

And it seemed to work just fine. Like Laura reported, not a lick of furniture to be seen, but all the lot's build mode stuff was there, except the fireplace. I moved Cyd Roseland and his dog into it, too, just to make sure it didn't crash or otherwise go funky with a resident Sim. No problems. At no time did I get any debug errors. I also noticed that the lot value went down in a likely sort of way. The lot furnished would have cost $98,000-and-change. Installed without furniture, the price was $37,022.

So, I give it a thumbs up! But would it be helpful to you to test this in an AnyGame set-up? Or doesn't it matter? If it would be helpful, I have a couple of AnyGames set up, including base-game only. It's on a different user account, but if it would be helpful, let me know and I'll test in a different configuration.

Thank you for testing this.

Yes, it would be helpful to test with other EP setups. I'm also doing my own testing, but it looks like most of the testing so far has been done with all EPs and SPs. Base game would be ideal.

I'll pick a lot to plop into the BG AnyGame, then... Will let you know what happens.

ETA:
OK, perhaps this is a product of me doing it wrong, because I've never actually installed a lot into an AnyGame before, only used it to build stuff in the AnyGame...but it doesn't appear to unfurnish the lot when installing a lot in my base-game-only AnyGame. Let me outline how I installed it, though, in case the problem is with me, not the installer. I did it about four times just to make sure I hadn't just forgotten to the check the "Remove Furniture" box. Here's what I did:

1) I opened the Sims2pack file with the Clean Installer.
2) Checked the "Remove Furniture" box and clicked "Install."
3) In the next pop-up, I de-checked "Default Installation" and then picked "Browse" from the "Select Installation Folder" drop-down and then browsed to the AnyGame's Teleport folder. I left "Sims2Tmp" as the file extension and left "Generate Sims2 Import File" checked." Clicked "Install."
4) The file was installed successfully.
5) Opened the AnyGame and used the "MiniGame" neighborhood that installs with a base-game AnyGame.
6) Opened the lot bin, pulled out the new lot (which showed just fine), plopped into 'hood.
7) Went into the lot in build mode...and all the furnishings were there.

Like I said, I did the whole procedure at least four times to make sure I didn't screw up a step. Same result each time. For reference, this is the lot I installed. However, if I'm not doing the install right, that could be the culprit here, not the program. Or perhaps I shouldn't have used the pre-installed MiniGame, although I can't see why that would matter...

ETA again: I went ahead and started up a new neighborhood within the BG AnyGame, just in case I shouldn't have used the pre-installed one. Still no dice. So unless I'm doing something wrong, I'm thinking the new feature isn't compatible (yet?) with a non-default installation? Maybe this wouldn't be an issue for someone who actually only has the base game, though?

Thanks. I'll have to take a look at that.

You're most welcome :-) The fireplaces thing is a shame but certainly something I'd be willing to live with! :-)

No, I don't believe that you're doing anything wrong. I had forgotten that there are two separate and nearly identical routines for installing lots, so I only changed the default installation routine.

This "separate and almost identical" duplication of the source code has never made sense to me, so I'm going to try to reformat the Clean Installer so that there's only one routine.

This means that it will take longer to fix than if I just copied and pasted the logic to remove furniture into the second routine, but it's something that I've wanted to fix for some time and this seems to be the right time to attack it.

I tested it with a community lot in an AnyGame that had all the EPs and SPs. Worked perfectly, Papaya Regime was deserted. I'm going to try it on my laptop, which is running up to Seasons, just as soon as I can force the previous version to uninstall.

ETA: Tried it with residential and community lots up to Seasons, worked just fine. Not a lick of furniture to be found. Yay!

Tested this apartment because I was curious if the toy dog on the lot would affect anything but it didn't, everything was removed properly. I've got all EPs and most stuff packs (FFS/Holiday aren't installed). Ran HoodCheck and had a quick look in SimPE as well after install, no issues. Thanks for this, it will be useful.

Fix: Should now remove furniture from non-default installations.

I have added a checkbox to the Clean Installer to remove furnishings from a lot as it is installed from a Sims2Pack. I have tested this on my computer, but I would really appreciate if a few people would test this before I give it out to everyone.

Please if you decide to try this, let me know which EPs and SPs you have installed and whether things worked as expected. If there is any problem with removing the furnishings, please include a download link for the lot.

Thank you to everyone who tests this and gives feedback.

[Update:] Removed. Obsolete. New version available later in the thread.

I hope that you don't mind, but I've created a new thread for this research, so that this thread won't be sidetracked by my research into this problem.
http://www.modthesims.info/showthread.php?t=502984

The new version of the Clean Installer has been released. If you are using one of the test versions from this thread, I recommend that you download and install the release version.

I've uploaded a new version of the LotAdjuster which has the option to remove furniture from an existing lot. Please note that this option will not work on dorms. Change them to residential first and it should work fine. I also disabled this feature for hobby lots, hidden vacation lots, etc. because those lots may require certain furnishings.