Everybody engages in behavior that is counterproductive or off-putting to others on occasion. For hobbyists and providers alike, I'm curious to know what specific behaviors from those on the other side of the aisle drive you nuts. From my perspective, one of the biggest offenders is lack of punctuality. I hate the "I'll be ready in five minutes" line, mostly when that five minutes turns into fifteen or twenty (I can deal with a five minute delay; at fifteen or twenty minutes there's a good chance I'm gonna bail).
What's interesting about these maladaptive behaviors in the hobby is that they tend to get amplified. I don't really know X, so when X does something that rubs me the wrong way, it tends to stand out because I don't have access to the whole of X's personality (good traits and bad). I try to keep in mind that everyone has their idiosyncrasies, and I'm pretty good about letting minor things go (I can bite my tongue with the best of them), but eventually a negative behavior that occurs with regularity becomes an irritant.
So, what are YOUR irritants?