Scammers operating on the interwebs are usually only interested in scamming people, not in contributing to forums.
As a result they usually use several monikers, have a very low number of posts (sometimes even zero) and often only recently joined a forum.
As a general rule with sales, always beware. But if you receive a private message from a forum member with zero comments posted to date (who possibly also only recently joined the forum), making you an offer or "recommending" a so-called "friend": that might be a scammer trying to bait you.
And remember: if something seems too good to be true, it often is. In case of doubt, save yourself the risk of becoming yet another victim. Walk away - it ain't worth the risk.