I think different people like very different things. A big pack lets people choose.
I uploaded a pack with hundreds of real photographs - didn't get a lot of traction, but was for sure what I wanted, and at least a few people downloaded it and use it.
The nude question is interesting - I personally go for "sexy, but not nude", because some of them do not end up being sexual slaves/workers. I actually made a mod (broken in newest version) that allows for clothed pics normally, flirting pics during the "meet" interaction, and then a nude/sexy pic during the "sex" interaction. Never got a lot of feedback - I make all my images for it and have a blast, but not enough interest to release it again. Sorry, wish I had better info for you.