I didn't have my first w/s experience until 1996, by which time I'd been punting many years and had had well over a hundred punts. I'd never even thought about it when a parlour girl asked me out of the blue if I was interested - she was interested in making an extra ten quid!
Of course it's unusual to be asked like that as it's not a spontaneous service and normally has to be planned / requested ahead. I went for it and enjoyed it, and it subsequently became something of a requirement for me. I have always received and never really given. The very few times I've been in a position to give I've usually failed to deliver!
I long ago gave up trying to analyse mine or anyone else's fetishes, although as I'm generally more submissive than dominant maybe that's something to do with it?
Although I say I never previously thought about it, when I was sixteen a mate gave me a girly mag and pointed out a letter in it where the guy had written that he liked his girlfriend Olive (I even remember the name!) to piss on him in the bath. My mate had pointed it out because he was disgusted by it - he remains a straight sex, no frills, big tits man and doesn't even really like arses! Whereas not only am I much more of an arse than tit man, the letter about pissing turned me on at the time. So maybe it all dates back to that.
To those who knock it, maybe they should at least try it first?