@furplekitty
If you don't want a specific person to know your outfits, then:
1) don't go into rooms / chats with that person.
2) don't save your outfits on IMVU (instead, save them locally on your computer)
3) make your default outfit something you don't care about
None of IMVU's built-in hide item / outfit functions work. That data leaks out all over the place. Otherwise, how would the computers / devices of those whom you are chatting with know what you put on your avatar on their screens?