Been playing with guys (any instrument) that are adamant to play this or that cover, but when they plays, sings it, they suck big time, and has left out important parts, sluggish, and slouch their way through it, and then afterwards, when pointed out to by all other members in the band, they don't get it. They get the "these-ones-goes-to-eleven" face when asked "well, why do you suggest songs for us to play that you can't pull off yourself yet?" DK effect running amok. And when singing/play something else provided of the rest of the members, in spite of being able to pull it off with flying colors, they'll go something like "can't get behind it" or "too easy, not a challenge" or something similar.
I e members that are adamant to still play songs that are too hard for them to pull off, but yet persists.
The worst thing is that they're not even trying to hone it further, since they can't hear what's missing. However, these things occurs only as fast as it is about cover material, not original material. Original material can come off either way. Always rehearsing to better it.
With these people, I am the first to split, instead of telling them to shape up. Because I've found out the hard way, it has dawned on me slowly, that it doesn't help no matter how hard they try. It's similar to someone who can't tell if he's in tune or not, but yet persists he's got perfect pitch. Can't be "rehearsed" or "practiced" away with.