Yesterday evening I went out to a local weekly jam session. This event started a couple of years ago and has turned into an informal outdoor concert, with a dozen or more pickers and a hundred or so listeners every week. The players are all local folks, and I enjoy playing music with them. But every so often something will happen to make the music hard to play.
When I arrived and joined the session yesterday evening, a person was playing bass and doing well with it. She knew all the songs, and played solidly on the beat. This really helped the jam session hold together.
After about an hour, though, she needed a break, and was replaced by another player. He got through the first number, though a little shakily. Then when a fiddle player kicked off the next tune (Golden Slippers, in G), the bass player started playing his notes on the off-beat, and stayed there.
Now, bass players play their notes on the ON-beat, not the OFF-beat. When a bass player is playing on the off-beat instead (like a mandolin's rhythm), it makes the music sound pretty weird. This time, it seemed as if half the players stayed with the fiddler's rhythm, and the others were wandering a bit between the fiddle and the bass. It was a pretty diffuse sound. I stopped playing after the first few beats of the tune, and decided it was time to pack up and go home.
I applaud all the folks who want to come out and play, but it's better when the bass player just plays on the beat. It's easier for everybody!