What you have to realise with people like this is that their agenda is totally different to ours, I presume most of us agree that regardless of whether you play doom, jazz, indie covers, weddings or something so original no one knows what it is yet the aim is to entertain the crowd? We try and play to a suitable crowd to start with to increase our chances and learn the songs at practice to make it run as smoothly as possible, other than that it's a jam and the crowd should appreciate it for that.
Now these guys are all about entertaining themselves so as long as someone is prepared to play bass, drums or sing with them then they are happy. There is a band near me where the whole band have this attitude which meens they gig regular too, I can't describe how bad they are but I have now refused to play on the same bill as them which I promise is not like me at all, they bring the whole evening down imo.