I've had this happen twice in the last several months at the Greek. Bet a futures line at The Greek which was obviously not a line error.. watch Greek adjust the price after taking the bet.. watch the line get bet down some more.. and then later on recieve an email saying the bet has been cancelled, because it was a "line error" and that the Greek intended to put up the exact current market price... not their opening line.
Most recent example: Brandon Jennings +4000 for Rookie of the year before the season. Jennings was listed at +4000 for several days, not completely out of line with general perception of the rookie class or the draft order. There was at least one other players listed at +5000 I believe. So, I bet Jennings. Jennings moves down to +2500. A few days later Jennings is at +1000. Then 5 days after my bet was placed, it is erased from my pending wagers and I recieve an Email explaning..
"Your wager on the above prop has been cancelled as it was up at +4000 when it should have been +1000."
So, they took bets on a line which wasn't an obvious line error. Then adjusted the line down. Took some more action over 5 DAYS and adjusted the line down some more. And then decided they will erase all pending wagers on this player, and say that the exact price the betting market has adjusted the line down to (+1000), was the line they intended to put up over a week ago.
Basically, the Greek lets the betting public adjust their futures prices by betting into them, and then cancels bets on any wager that they deem to have too high of a liability on. Keep the bad wagers made by the public in a betting market, and cancel the seemingly strong wagers made in the same market. That is one profitable business practice.