Heard it a few times and it certainly seems like something that would happen but is there any proof or real world examples?
Can an Appraiser just make something worth $20m based purely on their say so?
EDIT: Thanks some great replies! and yeah i was asking more about the tax evasion part than the 'modern art is bad lol' angle.
Someone I know was hired to do art sales at Sotheby's. They were extremely overworked, asked to do questionably legal things, and when they finally gave two weeks notice, were offered a promotion to dissuade them from leaving.
Hearing this situation, and they stories they would tell me made me think hard about how fishy the whole thing.