You may see the next big thing here. You may just come to enjoy the music of an unknown musician. You may be here to support a friend following a dream.
You are almost always guaranteed a good show once you walk in the door. There is always a cover and two-drink minimum to my knowledge, but you won't get too gouged here. And besides, you are here for the music so it should be worth the cost (cheaper than a concert where you would sitting much further away!).