Yes, that is true. If someone finds themselves a recipient of it too often, esp in quantity, they are going to end up penalized.
Participating in unsupported activities that are rife with fraud and ill gotten gold, tends to have risks. The risk of getting an account action is a big one.
Just like when someone puts up a grey wolf liver and it sells for 200k. While the AH is supported, something too good to be true is obvious gold moving and tends to get flagged.
Kind of like hanging out in a dark alley dealing with those shady goblin brokers. Someday you find out the TV they are selling you is stolen and the cops punish you for having stolen goods.