I have a different defintion of Nit: Someone looking for an edge is not a nit in my opinion. A nit is somebody who ask for the edge (spot) everyday and finally when the person steps up and gives the nit what they want the nit still doesn't play and ask for more
Example: This happened yesterday. My friend tells the guy you got the 8 and the guy says - give me the 7 I got 4k on me and if the game is right I will play. My friend knows he is in a good game. Pretends to think about it for a few seconds and says you got me you got the 7 just like you asked for get up there. Of course the guy says no thanks.
That is a NIT. They ask for a game that they think is way out of line because they think they won't get called on the game. When you can't stand hearing the NIT barking anymore and you tell them to get up there they stilll don't play.