If you like cheap, divey bars you need to get yourself to Teabags.  One of the very few bars that I've been to in Pittsburgh with a legitimate mix of people from all walks of life.  The bartenders are almost always lovely (only had one wacky one so far) and the patrons are delightful.  There's a pool table that is usually open, though it's not the finest table in town it fits the vibe of the place.  The drinks are dirt cheap.  The beer is always cold and the mix drinks are strong.  This place is just really perfect in my opinion and I'm just sad I didn't discover it sooner.