I know PhotoAlbums+ lets you password protect albums. But does it let you hide protected albums altogether so people are not even aware you have protected folders?
I believe so, yes. At least, you can put all your private albums behind a password. I think the word "private" appears in the app/tweak, but you can't open it to see specific folders until you enter the password.
In a way, that means people know you have private stuff on the iPad. But, without the password, they have no way of knowing folder names or what, exactly, is private.