A way to avoid the installation of unwanted content?

Hello! I can't say I have a real downloading problem. Following your instructions and with a little luck so far I've been able to fix every bug or bizzarre behaviour of the game. Actually at the moment I'm going to make a second factory reset cause I think I have too many .packs and too much custom content and the lagging is increasing badly.
A lot of stuff from the store is just ugly or even corrupted. There are clothes not showing up in the CAS (actually where the defective outfit should be there are just sim model's arms and feet and if you choose any of these defective clothes your sim's body will vanish, except for the parts not covered by the "invisible" gown/jacket/pants, etc).
I was wondering if there's a way to choose which articles to install from each set without installing the whole sets ending up with loads of horrible haircuts, absurd shoes, terrible forniture or defective outfits that will cause the sims to disappear.
In other words I'd love to keep in the game just the pieces I like and to get rid of that horrible store stuff that I never use and that causes many problems plus a neverending and painful loading in the CAS. Thanks in advance for any reply.

//EDIT: Erm...maybe by extracting the packages from each pack? But after extracting them they are hard to identify...