You don't need a thread. Here's the rule, verbatim, from United:

"Prohibition of sale or barter
8.The sale or barter or attempted sale or barter of any such mileage, certificates, awards or benefits other than as authorized and/or sponsored by United is expressly prohibited. Any mileage, certificates, awards or benefits transferred, assigned or sold in violation of the Program Rules, in addition to exposing the member to the penalties otherwise associated with violations, may be confiscated or canceled. The use of award tickets that have been acquired by purchase, barter or other conduct in violation of Program Rules may result in termination of membership, cancellation of accrued mileage, certificates, awards or benefits, confiscation of the tickets, denial of boarding with respect to the ticket holder, and, at United's discretion, completion of the travel only upon payment of an applicable fare."

A day or two ago, we heard from a GS who was complaining about his account being forfeited because he was selling GPUs.