A misnomer. Nice Guy is nice with an ulterior motive; he believes pretending to be a decent human being entitles him to endless sex with his unfortunate female target. Instead of openly expressing interest and then moving on if rejected, the Nice Guy prefers to attach himself like a barnacle to one woman, hoping that if he pretends to care about her feelings long enough, he'll get at least an awkward handjob in the bathroom. Nice Guy is then bewildered when acting like a friend results in his getting treated like a friend. The advanced-level Nice Guy will call his lady of choice a frigid bitch while simultaneously patting himself on the back for being so nice. Nice Guy fails to understand that acting nice in hopes of getting sex is not actually the same as being nice, and as a result can be found in his natural habitat martyring himself all over the internet.
If women really only dated assholes, then "Nice Guys" would have no problems getting women.