One of the girls I work with moved here from Dublin, she said in passing that her friends thought Belfast was crap for going out. This is the exact opposite of the general feedback which I normally hear. I think I have found out why, she likes to wear trainers when she goes out, she likes live music and traditional pubs, and doesn't like the 'poser bars' (her words) like The Apartment and Bar Bacca.
I pointed her to a few sites which I was amazed she had never heard of, I suppose you assume people pick up on these things, so here they are:
Fastfude

Alternative Ulster

ATL Gig Guide
And apparently 'according to one of my colleagues' this is a nice bar with a sensible attitude to those who decide they would prefer not to worry about what footwear they decide to wear when out for a night.