Even in a gleefully negative comic there is optimism although it's slightly hidden: It comes out through a comic character's sheer tenacity. He keeps going and trying to find some sort of fulfillment regardless of his perpetual failure record. That's a form of hope a form of optimism. Really hokey I know but it's true.
With Portlandia I don't think our intention is always to find something funny. Sometimes the humor comes from taking something really seriously. We're okay with making somebody feel uncomfortable or uneasy.