How to do this diplomatically...

There was a band that played a show we used to do regularly a long time ago. They were a 3 person group with a bazouki player, a guitarist, and one person with a pair of bones. Not a bad combination of instruments, certainly. The bazouki player was OK, the guitarist was OK, and the bones player should have learned how to use them instead of holding one in each hand and banging them together in the simplest of rhythms (4/4). Now, this in and of itself is not all that bad, but add to this that none of them could really sing very well (one was completely tone deaf), but sang they did, and that they did not stay on stage (or even near one another, for that matter). The doppler effect of them not being able to hear one another made them off time, and added chaos to the cacophany. Even with their attempts to be engaging by coming into the audience, they seemed to miss the fact that this alone would not make that happen. They did not make eye contact, they did not smile...they simply wandered around a little like zombies and played off time and off key.

In their defense, they were working for one of the biggest skin flints in that particular arm of the performing business. They were likely asked to "form a group" by said management, and were likely not getting paid anything at all.