For a while there, the gem "cartel" we had set up was working well. We were making tons of sales, and everyone was happy. Then another new person entered the market. They are on about 18 hours a day on weekends and during all peak hours on weekdays.
One of the guys who I had my "cartel" with is gone. I talked to the other one about the new competitor. This new guy posts one gem at a time, and almost instantly undercuts when you post. The other guy thought it was a bot after wathcing him for an hour go to the same spot near the mail box and in the same spot at the auction house.
I figured I would watch him. I also let him know that I was watching him. At first it looked like he may be botting. Then it seemed like he noticed me. And he ported to Dalaran. I followed him to Dalaran. He logged off. A minute later he logged back on and went back to Stormwind. I followed him and he went to the Dwarven District. When he noticed me, he went back to trade, then again to Dwarven. Then back to Dalaran. Then back to Stormwind. Finally he went to the Firelands (assuming for dailies) and then on to Exodar. Makes me wonder.....what is he hiding? What does he care if the competition can see him. This does seem very suspicious to me.
In the meantime, I undercut all of his gems with a single gem. Then again. And again. I will play at his game until he conforms or gets the fuck out.
I whispered him about a whitelist and he did not respond. Prepare for war.