Let me assume you are not a newbie on bass. Let me assume you are pretty damn competent. Let me assume you have even made a living at some part of your life with your instrument. What would your minimum standard of competence be for other players for you to want to play with them, even just jamming ? Example: Lets say you said, "Lets jam around in Dm.". And then it was evident, that say perhaps the guitarist, did not really know what Dm was. In fact all you got was, "Oh, I just play by ear." And then you realize he just ain't cuttin' it. Would that hack you off? I mean, I understand playing with someone just to improve their prowess on their instrument may be charitable for a while, but I think that will wear very thin (probably pretty quickly) unless you are there as an instructor of some sort. What do you think?