I have recently installed some fine houses but they came with many many MANY unwanted CC. I found this great tool that is Custard Cleaner. My question is whether something bad happen if I run my sim3pack lot (that I have already played with) and remove some unwanted CC and then proceed to play again? Is it only meant to be used on sim3pack that haven't been already installed? Will it mess my saved game? I only want to get rid of the CC i don't use (obviously).

Any help will be appreciated.

hmm i am not sure if thats noobish but
you could load the house in game - put all unwanted cc out and save it to the libary in that state you like it. then you can remove the unwanted cc and have your costumized version of that house. thats 100% save to use.

also i thought i read that if you want to use the original (for whatver reason) normally the cc thats not there anymore (cause you removed it) should be replaced by other items when loading the house. you should delete the cache files then before you load the save again. (especially the compositorCache.package and maybe even world caches for saves in costum worlds - Windows only!)

but i peronally would go for the first "easy" option .