Yesterday, I basically made ~50k by ruining the day of 5 people while sniping the AH. Some of them contacted me afterwards, like this guy (in french): http://i.imgur.com/DIF53g7.jpg

Translation:

HIM: son of a bitch.

ME: what?

HIM: do you have a bot or what?

ME: no

HIM: i sold [Rylak egg] to the wrong price

ME: i'm just looking at the last page of the AH

ME: yes, i saw that

HIM: i didn't even have the time to cancel

ME: :]

ME: that's too bad

ME: if you want I can sell them back to you for 80% of the market price !

HIM: lol

HIM: the only thing i'll do at most is to spit in your face, keep the eggs, i hope you'll shove them in your ass to lay them again, meanwhile i'll report your bot to a GM

I don't like pissing people off, so what do you usually do to explain them they've just lost a lot of money without making tons of enemies? Also, how do the GM usually respond when they receive this kind of request? Have you ever been approached by one?