Sims 3 - missing leg on every new game

@Alex_Zokas  It really could be anything, unfortunately.  I mean, it's more likely to be clothing, but it could be an accessory or hair, or even perhaps a custom skin.

If you want to test quickly, you can use the 50/50 method on any .package-based custom content, as in, the files in your Mods folder.  For Sims3Packs, you can try Method by Mell, described in this article:

https://sims3.crinrict.com/en/2011/01/tutorial-how-to-get-rid-of-unwanted-custom-content.html

But instead of simply examing each .dbc file in the launcher, you'd load the game with that file present and find out whether the issue was still there.  Once you figured out which file was causing it, you could go from there, either uninstalling some of the items in that .dbc file or ditching the file altogether and rebuilding its content.

It's also a good idea to clear out everything in DCBackup except for ccmerged.package, which is necessary to make premium store content work.  The other files are only useful if you want to upload sims to the Exchange and have your cc stick to them, but it's of course more polite to upload without cc.  The reason this is important is that bad cc can lurk in these files too, and sometimes flushing them is the only way to get rid of the bad files entirely.

In the future, when you want to add new cc to your game, it's helpful to test in a clean user folder: move your entire Sims 3 folder out of Documents\Electronic Arts and onto your desktop, open the launcher to create a new folder, install the content there, and test.  If you notice an issue, you can trash the entire new Sims 3 folder, with no harm done; if everything is fine, you can put the old folder back and install the content there.