Unless your adding a bunch of Hentai to your "add to watch" or "completed list" then I see a reason for the concern of privacy. But even then, it's not like anyone really cares what you are watching. & Besides that point. You can simply go to you library and click private on the certain Anime or Anime Hentai you don't want shared with others to see.
I agree with Thorik.
Folllowing or being followed.. It's just people wanting to add someone with similar interests in anime, and share thoughts with one another on random occasions about the anime your both watching. So whats the harm there?
And @ you females using real pictures. If your afraid of a bunch of guys adding you, then bugging you. Don't add your real avatar. Simple right?