I apologize with both VD and Elotro for having "copied & pasted" their answers: I have a very close feeling with these two gentlemen and I do hope
they didn't care for that.

As VanDattum said "the more realistic the scene looks (like that it could happen in real life), the more arousing it is". But for me this means that the best plot is girlfriend/boyfriend when both of them are enjoying (specially her). Enjoy for him does not mean physical pleasure, but emotional link with the girl, who can be (who I prefer to be) really cruel. So I also prefer to see him trying to resist, but unable to stop her. willing to be in a helpless position, at least until the torture last.

naked vs clothed vs scantily clad [both the ballbuster and the guy]
both are ok.

do like to see him 'enjoy' it, or do you like it when he 'resists'
As I already said, they are not incompatible! Well said.

do you like a silent ballbust, or do you like it where she teases, mocks humiliates....or [deliciously, for me] where she shows mock gentle concern and asks if his balls are hurting.
I prefer to hear her talking, I like also when both of them are talking explaining their emotions.

do you like all/any age of ballbuster/ ballbustee....or do you have a preference eg: i like it where a mature women in a position of power, ballbusts a much younger, preferably much shorter guy.
do you prefer a petite girl to bust a beefy big guy, or like a tall amazon to bust a weedy guy.
Whatever size is good. Mature Domina Vs. young boy is also welcome.

do you prefer her to look haughty and contemptuous as she does the busting, or do you like her to laugh and giggle.
Laugh and giggle definitely.

do you prefer them to seem like total strangers, or do you like to think of them as girlfriend and boyfriend. the dungeons are ugly and cold (compliments Elotro That’s it).

do you prefer to see a single devastating couple of kicks or knees....or do you like to see multiple kicks for minutes at a time.
Multiple kicks or knees are less likely than few well done shots.

do you prefer to see a guy busted by just one, or by more than one girl.
One is enough.

do you see yourself as a spectator, or do you imagine yourself being busted in place of the guy in the clip?
In place of the lucky guy.