I think it all comes with experience. I personally was freaked out the first time someone did it to me and very grossed out the first time a guy asked (or guided my hand) to do it to him. Well, I remember the feeling of excitement to, knowing this was a taboo area for me. Well the more men I got with I liked to give them that WOW FACTOR if I found he was a little shy. You can tell the difference... fun to see if they will do what you asked! My excitement during sex comes from seeing my partners reaction to my actions. Personally a finger is much more pleasurable then all out
Anal sex. Same as any other sex act.... if it is done everytime and predictable... becomes a bad thing for me.
Like speghetti... love it but dont want it for every meal!