Its a nice guy who isn't perceived as nice by his surroundings, for the sole reason of being angry. Might be a transitional stage from being a nice guy to assholery. The reasons for anger are multiple - ranging from plain rejection to disliking of whats going on in the world to observing general flaws in human nature and relationships. Symptomes include:
- angry/non-calm complexion
- lack of motivation
- has a high value for truth and expects the same from others
- upon meeting a girl, he will be always polite and try to be a gentleman
- when she tries to take advantage of it, he will break all contact with her. And then the cycle repeats with another woman
- ignored by most women, for the reason below:
women are unable to decide whether he is a "nice guy" (who would do anything to please the woman and get burned in the process) or a "regular asshole" (who treats the woman badly, and who is recognized by her as THE MAN). Neither does the "angry nice guy" fall into the middle category of guys (which is considered to be ideal, as the guy will respect and care for his woman, while maintaining authority in the relationship). As women are too lazy to over-analyze this, they give up and move on to find someone more simple to understand - a nice guy or an asshole.
In sum, even though an "angry nice guy" has more dignity than a nice guy, he is still a nice guy to the core. The only difference is that he is not getting any ass, and more honest than the nice guy.