Exactly!

At our Folk Club we have some singers who prefer to sing unaccompanied, and you often find the most inept 'accompanists' joining in and ruining the atmosphere - and they are oblivious of it!

However, there are others who ask for accompaniment, and I'll join in at that point.

What I find very distasteful is those who 'join in' and quickly appear to be taking over someone else's 'floor spot'. It's one thing joining in with an accompaniment when asked, but rather ignorant to try to overshadow the performer whose 'spot' it is. Playing an instrumental verse in the middle of a song isn't the same thing - it's an acceptable contribution (assuming the singer wants it, of course!).

I have to admit that I've been guilty in the past, but have learned the error of my ways. These days people specifically ask me to join in, I'm happy to say.