Hamsters got another one.
Big Bad John?
OK – you want real answer? Lobo
I’d say Captain America. Those military types are a randy bunch.
The Thing?
Man, talk about a rough road. I hope he pays those poor girls well.
I was guessing Aquaman. I just figured that most of his girlfriends drown if they go down too long.
Batman – if he’s prepared.
sorry–couldn’t resist.
If I recall correctly, Plastic Man is little shifty. I could see him visiting a prostitute.
The Flash – cuz there is no way he can keep a girlfriend if he is THAT fast!
The Comedian from Watchmen does patronize prostitutes (at least he did in Vietnam) and the government pretty much paid women to sleep with/have relationships with Doctor Manhattan so they were sort of like prstitutes…
As far as from the mainstream books, I’d say Marvel’s Nomad would and the Hulk during his Mr Fixit grey Hulk in Las Vegas period probably did (whether he paid them or not is another story).
I was thinking Aquaman, too, but more because of his low self-esteem.
Daniel
The Punisher, on at least one occasion that I can think of.
Daredevil. He’s dated drug addicts, assassins, porn stars…why not?
Probably Robin. Who else would do a nerd in leotards?
The Green Whore-Net. Who else?
I came pretty close to spitting my water at the monitor there, Kalhoun, nice job. 
Mr. Fantastic probably doesn’t have to pay women to sleep with him…
Heh. It’s a gift.
And let’s not forget Family Guy’s visual evidence of Superman in hell, playing cards with Hitler, Al Capone and John Wilkes Booth.
[Peter: Superman? What are you doing in hell?
Superman: I killed a hooker. She made a crack about me being faster than a speeding bullet, so I ripped her in half like a phone book.]
I don’t know much about comics, but I would have guessed the same…before I read (on this very forum!) that The Flash has the power to vibrate his body. Any part of his body. Presumably at any speed.
Thanks to the SDMB my ignorance was fought, and I’ll never question The Flash’s erotic abilities ever again!
Actually, I can see Bruce Wayne indulging himself with the occasional $10,000-a-night professional, just to drive away the loneliness.