You don't have to post any pics you don't want regardless if it's in the private gallery or public, you post what you're comfy with. I would just make sure the descriptions/names of your private gallery are clear. Or have a little blurb about the photos on your main profile so the clients know what to expect.
I do have some very explicit, spread eagle, toy pics in my private gallery but I used to cam which is why mine were I'm there. Really it's down to personal preference and I don't think it's necessary to have those types of pics.