At least in AE, you can certainly call a man a slut as well. It gets a bit more complicated with "bitch," though., ;-)

A male whore is used in that meaning , as well... :-)

P.S.: other options would be:
horndog
whore (jokingly, of course)
stud
whoremonger
satyr
etc.

Yes, you can say it! But dude is right (yes, dude, I will kindly allow you to be right, if that is alright with you ;-) ) - you could get into trouble if you use "bitch" to refer to a man. This would have homosexual overtones, to say the least.

@Mary: thank you kindly. :-) But more than "homosexual overtones," bitch used toward a straight man or in a straight environment has very demeaning qualities.

What happened to the good ol' s. o. b. ?? :-))

Learned something new again today in LEOLand - I didn't know you could call a man "slut" - what about gigilo ??

a gigolo is a professional, Carly. :-)

@Helmi(e): an "s.o.b" can be a lot of things, not just a slut. :-)

Well, so are whores, dude :-) Can a male be "trash(y)" ?

"man whore" is also a phrase people throw around a lot these days.

i also feel that you can call a guy a "bitch" but it has less of a sexual/promiscuous connotation, and it means more like, mean and catty in a feminine way

finally, if you call a man "trashy" or "trash" it sounds to me like more of a class-based insult than anything. this is also probably true for women, but with women "trashy" also has a pretty clear nuance of "slutty" as well

@Carly: If you were to go to West Hollywood, for instance, you'd find all kinds of trashy little (male) sluts in varying degrees of masculinity (or femininity, depending). :-)

what's trash in german???

@dude, :-))) I was only in Hollywood once, and that was about 28 years ago - guess I was too busy keeping a hopeful eye out for STARS, to notice whether any trashy males were around :-)

manwhore is perfectly fine in AE

"He's a male bimbo... He's a mimbo!"

I heard this a few times watching Seinfeld. Maybe not "official" English, but still quite fitting in my opinion.