I once had a guy come up after a show to slag off my guitarist. The bloke seemed to be a clone of "Brittas" from the telly.
I politely listened for 5 mins as he told me I needed to replace the guitarist with someone who knew how to play. He then said he would be happy to come along to a rehearsal to help....
Then I took great pride informing him that said guitarist was beyond grade 8 standard and played in one of the military bands and that I wasn't actually aware of a single piece of guitar music in existence she couldn't sight-read flawlessly. (She was a bit of a non-improv sight reading robot, but I've never had a punter complain about nailing solos perfectly!).
She really was phenomenal and the bloke was a twat.
I loved that band. The drummer was great. Not in a particularly technical way, but there was that wonderful bassist & drummer shared intuition that happens far too rarely.