A few of you guys are confusing weak players with bangers, imo. Someone who can't run an open table without clusters is not automatically a banger. Hell, I've been playing for 15 years, and I can't do that reliably. Someone who doesn't know what going 3 rails means is not automatically a banger.
The general "player" ratings are this:
D
C
B
A
Shortstop/Open
Pro
A banger is not even on the scale.
A "banger", imo, is someone who comes in casually to a pool hall with a group of friends or a date just to bang balls around. They have no concept of cue ball control, pattern selection, or game strategy. They don't even know these ideas exist. They might have heard of english, but think it means if you put right spin on the CB, the CB will go to the right after hitting the OB. They also play by crazy rules that they heard about from their banger friends, such as if the CB lands on the rail, you can move it a distance equal to the butt of your cue.
A "D" player is someone who is just starting to get the pool bug. He graduates from coming in with his buddies, and actually tries to learn the game. He still stinks, but he is trying to learn how to control the cue ball. He doesn't know many shots, and when he sees an advanced shot, he won't know how it was hit. He will generally try to be competitive, in either weekly $5 tournaments, cheap gambling, or league play.
To summarize, a "banger" is someone who has absolutely no desire to learn the game, and literally just comes in to bang the balls around the table. A "D" player is the lowest level player that legitimately is trying to be competitive and learn the game.