A person who automatically assumes someone is fake, a douchebag, an asshole, a whore, or any other insult, for not liking them, going out with them, or some other egotistical reason.
A person is this especially when they say the person is any of the said insults.
A person is even moreso vulnerable to this term when the person under condemnation by the glooch has a legitimate reason to respond to their egotistical request.
Steve: He doesn't like her, and she wants to go out with him. So for some reason, she keeps calling him a fake douchebag who thinks he's higher than everyone else when he's just a kid like everyone else making use of what he has. She backs it up with every little mistake he's ever made, even when they're not related.
Bill: What a glooch; she apparently thinks her attitude will make up for the fact that she got denied - not because she's not good enough, but because he already has another girl.