I had a bass player once...easy enough to get along with, at rehearsal it seemed ok but we play loud in a small room so who knows? He had impressive tracks from his previous band so I thought knew how to studio track.
I bring him into my studio and every note is buzzing so badly that there was little to no note. He also simplified every riff to the point where he was riding the open string all the time, causing all kinds of minor 2nds. I offered my bass but he insisted no, it had to be his buzzy bass. I created TABS so that he would know the chord changes but he tossed that aide as an insult. So annoying that he couldn't clean that stuff up and actually learn the riffs. I think the last band was another bass player because this guy was so exposed when under headphones.
I still was going to be patient, but the guy said he didn't have the cash to buy new strings and a setup. My empathy ran out when the very next conversation he showed me all the new tattoos that he was getting all over the place, describing the 1000s of dollars it would take to finish these tattoo projects. When we tossed him, he was seriously bewildered.
moral: Most players like to jam but have no idea how to record; ie keep their instrument in tune, learn the material, and play in time.