Just Don't Buy. You may probably get temporary, illusive benefits but will ultimately lose all of your money and more if you take such "charter for cheats", and nobody will be on your side. It's not worth adding a bloody touch to your "airline credit history" to filch a E+ or lounge access.

United does track those sellers and buyers. Most of the buyers will got their MP account banned (if not upon delivery of the trial upgrade) lifetime due to failure of (multiple) verification of submitted documents.

Rest assured, MP does have a relatively strong verification/audit process between major airlines especially 5US carriers which they won't admit (who will? LOL) in public. C'mon, this is United. Don't you see that seller was hiding himself from place to place?