This page in a nutshell: In discussions, people will disregard irrelevancies and stick to the evidence.
Mooning the jury (or cheeking the beak) is displaying disrespect for those who will decide an issue. It is an efficient way of setting oneself up to lose. Theoretically, an unbiased set of editors, administrators, or arbitrators will disregard such irrelevancies as mooning (after all, all humans have bottoms) ... but the reality is that human beings make judgments based on other factors than the bare facts. Hence, don't moon the jury.