Hi, I'm genuinely a nice guy in real terms- I treat my male friends as bros, I'm always looking out for them, and I make friends wherever I go and look after my colleagues and family.
However I never do the nice guy crap with girls- girls don't notice me much because I'm physically unattractive- the offers I do get are from girls that hit on my friends then work their way down to hitting on me, so obviously I'm not interested.
I do treat girls nicely, but the same way as I treat my male friends- I'll buy a girl in my social circle a drink if I'm buying all my male friends a drink too, and I'll give polite chat, but I'll also take the piss out her in a friendly way (and encourage the piss to be taken out of me) in the same way me and my friends take the piss out each other. If I'm going to make a rude joke, I'll still make it in the presence of women.
I don't try to act all sensitive etc because I'm not.
I am a gentleman in the sense of not hassling women (I never really hit on girls), if a girls drunk I'll help her into her taxi and hold doors etc, and if a guy in a club hassles her I'll back her up, but I'm by no means a wimpy, self-pitying 'nice guy'.
My idea of being nice is treating everyone with respect- even if I do make crude jokes, I'll notch it down if it's clearly offending someone.
I treat women the same way I treat my male friends, or most people which is generally nice.
I might have tattoos, a ****ed up sense of humor and listen to death metal but I'm generally kind.
The typical 'nice guys' I know are little, whiny douchebags. If a girl doesn't like you just get on with it!
(Note I whine about not finding decent girls that like me because I'm ugly- nothing to do with this nice guy crap).
Man up!