Good question.
Haven't really been turned on by it. I'm thinking that it's usually fake or just pissing, although I've seen some things by "experts" that lead me to think it's possible, even if most women don't do it (or even care to). My gal's never done it, and no woman I've ever been with has done it. They didn't seem to think they were missing out on anything.
I might get into it and turned on more by it if a woman I was with did it and it was obvious that it wasn't just piss (like if it felt and/or smelled and/or tasted different - or obviously came from a different spot).
But as far as women squirting anything, lactating tits can be VERY nice, and get me going. Tittyfucking a lactating lady might be a nice thing.
But as it is, I'm just happy if the pussy is nice and moist and she has her usual 2 to 3 big O's.