what makes a dive bar?

Over on Leaping Point I talked about finding a good dive bar in Melbourne, something I hadn't even realized I missed in New Zealand. A bar in a small city building, with dirt on the floor and tacked up decorations on the walls, with a pool table and a few old couches along with the bar stools. A bar with grit rather than seediness, a bar where the young and aimless can mix with the older working class without any thought to the matter.

It helps the atmosphere that Australia, or at least Victoria, still allows smoking in bars. You can't have a real dive bar without smoke hanging in the air.