Don't lie. But remember you may be wrong. And never sneer.

People remember sneers. A digression: I was once in the audience at a concert in a small venue. The main attraction was a very well regarded group who were on the up, and a support group who were ok, but not going to make it. I can remember the way the successful group had this scornful sneering attitude towards the others, and genuinely upset them.

Years later, if I was ever involved in booking I'd be against booking those guys. Musically they were and are pretty good. But sod them. (And I won't name them because maybe it was an off day and they were tired or whatever. And maybe they've got a libel lawyer anyway.)