Its all Bollocks. The bottom line is if they want to bust you, they'll bust you and if they dont, they won't. If the publican thinks you'll bring in drinkers he'll take the risk. When he gets found out he'll kick you out. The one the cops can't handle is when they walk in and everyone is singing a different song or playing a different tune. Then you are unconnected individuals singing or playing to yourself. And if you all pretend to be deaf it really does their head in. Another trick is to stop playing and start miming when they come in. You've got to stay dead pan and not crack up. It totally freaks them out. Or start singing hymns and claim to be new age christians. Tell them you'd all like to talk to them about Jesus. You won't see them for dust!