I'm not sure if I'd qualify Weiner as bitter. His comics tend to be pessimistic, sure, but a lot of that is the rule of funny. Comedy is about human pain.

Weiner talks about things that may make other people bitter and so those other people may expect him to be bitter because he acknowledges those bad things. Instead I see Weiner see the world as it is, exaggerate it for the sake of satire and then delight in it. You don't need rose coloured glasses to be content.