You have to be more careful than ever when buying lift tickets. I recently purchased some lift tickets from craiglist. They looked legit and checked out. When I went to the mtn and brought them to the ticket counter, they said, “Where did you get this.” The # on the voucher was from a batch of 180 tickets that the mtn gave to a person/organization raise/donate for charity purposes. The seller was selling all of them. The mountain was not happy to say the least, and are looking to press charges against the individual/party involved. They did honor the voucher, but not after some extensive questioning.
Bottom Line, Buyer Beware.
Craigslist is a great place to find lodging though!