I need some opinions on an idea/scenario to uninstall unwanted DLC that won't show up in the Launcher.

Say I installed a house and it came with an ugly broken toilet that wasn't mentioned and I don't want it. I can't get it to show up in the launcher or maybe the launcher won't activate without an error.

Multi Sims3Pack Extractor by Delphy allows you to take out the insides of a sims3pack and look at it as .packages.

It's possible to use S3PE to open and look at the DCCache files were there are equivalent pieces of the download and its pieces as scattered indivisual files with the same instance number.

Is it therefore possible to open that houses Sims3pack with Multi Sims3Pack Extractor to look at individual pieces, find the toilet I want gone and then search for its instance numbers in the DCCache files and then delete them all, therefore uninstalling them, without screwing up your game?

In theory this should be possible, yes, but it takes a lot of time and effort. And only if this toilet is indeed a third party custom one and wasn't installed into the .ebc files. These are encrypted and contain Store items and S3PE cannot open them. S3PE can only open .dbc files or decrypted .ebc files.

There are other steps you can go through before you go the .dbc route with S3PE, though.

First, make sure that the toilet is indeed a separate item in the Sims3Pack. You can look at the contents of Sims3Packs with Delphy's Custard program before you extract them with the MultiInstaller. If the toilet is a separate item that shows up in Custard and comes as a separate package file after extraction with MultiInstaller you can go to ...

Second, make a new user folder by renaming your regular one temporarily and starting the Launcher afterwards. This will create a new, clean user folder. Copy only the .dbc file(s) from the old user folder into the DCCache folder of the new user folder and start the Launcher again. Sometimes the Launcher fails to show items when there are two many objects installed and shows them again when there aren't that many items in the DCCache folder. If the toilet shows up then you can uninstall it the regular way with the Launcher.
If you've got a lot of installed stuff you can even limit the strain on the Launcher by only placing one dbc file in the new DCCache folder and go through them one by one. Dbc files are called dcdb0.dbc, dcdb1.dbc, dcdb3.dbc etc. Place only dcdb0.dbc in the new DCCache folder and start the Launcher. If the toilet doesn't show up remove dcdb0.dbc and place dcdb1.dbc in the new DCCache folder and start the Launcher. Repeat this until you find the dbc file that contains the item.
It may be that the Launcher doesn't recognise the dbc files that are numbered higher than dcdb0.dbc when dcdb0.dbc is not present. In that case rename all the higher numbered dbc files to dcdb0.dbc before you place them for testing (dcdb3.dbc, for example, to dcdb0.dbc) in the new DCCcahe folder. Just make sure that you rename them back to their original number when you are done with them.

(There could be another scenario, though, namely that the toilet is not a separate package in the Sims3Pack and has been merged into the lot file itself. In that case it's going to be difficult to identify the respective resources in the lot package)

Thank you.