Buying a Domain Name in forums

Buying a domain name in various forums is sometimes very tricky. Someone is selling a domain name for example MYIV.COM requesting to post offer or by PM (private message). First interested buyer will post $500, $600 from the second buyer, $700 from the third buyer, and then later on you will see a post from the seller "High Offer $2000 received, BIN $4000". I don't know about you but this is fishy transaction to me, and I stop posting offer. As member of the forum, you are not allowed to question the owner post because "not related to a sale" or "not productive question" or other reasons. This is happening to any domain name forums that you might be part of, well at least one of the forum.

Question to other domain name investors. How do you handle and approach this scenario?