I've been paid nothing on a few occasions. And, without wishing to sound like some big head ego type person...it did annoy me. As a band its nice to get a few quid, for example to put towards recordings. If we had been told in the first place that we wouldn't be paid and given the reasons why I'd have been cool with it. But when you don't get paid blatantly because the promotor did a shit job of promoting, got fuck all through the door and then had to give all the money to the headline act - its just not on. Either do a good enough job of promoting; or be explicit when you book the bands - "guys, this one isn't going to be a paying gig because of such and such a reason, hope you still want to play"