i think the opposite is actually true: sweet guys are in high demand, and so are always already in relationships. every really nice guy i know, is either married or in a relationship. there's only one exception: a really nice guy who is painfully shy to the point where he maybe talks to a new woman twice per year. and he has a two-inch p***s. and he
still spends more time in relationships than out of them...if he wasnt too shy to get together with all the women who come on to him, he'd never be single.
on the supply and demand front, it's interesting to note that the majority of single working-class egyptian guys are very sweet indeed to women, since demand for women far, far outstrips supply (most working-class egyptian women are not open to having boyfriends, and will get married without ever having had one). the sweetest guys are the ones who end up with the few women willing to have boyfriends. once married, things are very different: guys who are naturally sweet stay that way and make lovely husbands. those who were putting it on to get a woman, revert to type.
the upper class (about 1,000 cairo families) which is very westerned, is more like the wider world in general...ie, women tend to care more about relationships than men do, so supply of potential girlfriends outstrips demand, so the men need to be less sweet (and generally are). guys who dance salsa are more in demand, so tend to be the biggest playas/a-h*les (though of course some are nice anyway).
agree absolutely!

nice guys are defined by their behavour, not by their own perception of themselves. unfortunately, some guys are such complete a$$h*les that most men believe that simply not being a user/playa/abuser is enough to make them 'nice'. whereas probably 20% of guys are a-h*les in realtionships, 10% are really nice and the other 70% who think theyre nice are actually somewhere inbetween.
a nice/sweet guy:
- calls often, and definitely whenever he says he's going to
- remembers life events, major and minor (birthdays, interviews, doctor's appointments) and remembers to celebrate or show concern, depending
- happily demonstrates affection in public (i dont necessary mean major PDA, just hand-holding/hug/cheek kiss etc) and private, without always wanting it to lead to sex
- wants to make you happy enough to go that tiny bit out of his way (by sending flowers, forwarding you a link to an interesting article, buying your favourite chocolate bar when he gets his newspaper, tearing an article out of that newspaper for you, cleaning the kitchen floor when it's not his turn)
- supports you when bad stuff happens, rather than disappearing til the problem has
- is polite to your friends out of respect for you...he doesnt have to spend time with anyone he doesnt like, but would never be mean to anyone you care about
- expresses his anger without ever being mean or hurtful (for me, the key attribute of a nice guy is he never seeks to hurt you, even if he's hurting)
- enjoys spending time with you, but respects when you cant spend as much time with him as he would like
- considers your feelings and apologises when he gets it wrong
- if you live together, automatically takes responsibility for and does his share of any housework/chores/childcare - ie, half. he doesnt think he's doing you some sort of favour by 'helping' with the housework.
it always amazes me that more guys arent nice. it's really easy, not time-consuming and makes women so happy. and a happy woman = a sexually active and experimental woman = a happy man.

there's literally nothing sexier than a man with a vacuum cleaner, lol.

note of warning: like azana's 'horny grandfather' doing something nice only in the hope of getting laid is not nice, just creepy...
there's nothing on the above list that the average woman in a relationship wouldnt be doing as a basic baseline, imho...
i wish i had £1 for every time a guy behaved badly, then tried to make up for it in some lame half-hearted way, and
then went around whining about how "women only love b*stards". or hates you simply because he tried to go out with you, and you didnt want to. or stuff like, "i know you planned to go out with your friends tonight, but if you really loved me youd stay here with me" is pathetic/passive-aggressive, not nice at all.