I run a PC who is a girl chaser. Half-Satyr with a 22 Charisma, and points specifically in seduction.
We play it light. We have him make a roll to see if he remembers the name of the girl in his bed. She often turns out to be someone he should have left along (most recently the daughter of the Captain of the Guard.)
The "unwanted consequence" he faces is, as some would say it, "A matter of wife or death!" (i.e. a medieval version of the old shotgun wedding.) As far as he's concerned, jumping out of windows to avoid a husband/father is for amateurs. He frequently has to flee the city.
It's a plot device, a bit of game color, and we leave all the fiddly bits to occur behind the scenes. And I think that's the way it should be. Let's admit it, we can role-play porn if we like, but there's sure to be better written stuff out there for free on the internet.
The only time we've actually had him roll that Perform: Seduction skill check, I actively wanted him to fail. Against most people, a +21 is pretty much unstoppable at our levels, but this wasn't "most" people and I was really really hoping to roll a 1. I didn't, and now my character is out of play for at least 3 days of game time, and probably more like a week.
That, my friends, is an undesirable consequence. As for the rest of it? Was she hot? Was she not? Did you get some? Did you get away? Did you get away with it?
It's a game. It's make believe. No harm, no foul, no matter what.
Fantasize all you want, but like I said, there's better porn out there if you really need that sort of thing. But porn, in my experience, is best enjoyed in private, not at the game table.
But it says something odd about us and our culture that we can openly discuss fantastic ways to slaughter armies, to hack and slash our way through people by the score, but to describe a "successful" date has people hopping around like they were barefoot on a sidewalk in August.