I get what you are saying - scamming is a real problem; even among those we consider to be on-line "friends". From a recent admin post, it is apparent that someone (or more than one) stepped over the line. Certainly, the forum owners can't be held accountable in any way. Ultimately, it has to be up to individuals. A transaction in a forum such as this requires a certain amount of trust between inmates. At some point, one side has to send money and the other side has to send an item. A risky business if one of the individuals is not a well-known and established forum member.
In any transaction, I want any price negotiations, exchange of addresses, payment options, shipping discussions etc. to be private. I guess the question is when (and how) to take things off-line via PM or email. Any suggestions or guidance on that?
I have done two significant transactions through this forum and both went well for all parties. In one instance, I bought a topcase and rack from a well-known member and there were no issues. Shipping was a pain and that had to be worked out via email. Not a huge cost but more than I would be willing to throw away - I wouldn't have bought from a newbie with a half dozen posts. The other was the purchase of a bike and trailer. Complex negotiation that couldn't be done through the forum. Cross-continent fly-and-ride so lots of legal documentation, deposits etc. I had to do whatever I could to ensure a fiscally safe transaction. (I was delighted with the outcome!)
For a purchase, I would prefer to ask/answer any questions about the item in the "for sale" post and establish that I wish to buy the item at the agreed price. I would want to take things off-line at that point. That lets the seller know that he/she has a likely sale and other readers know that the item is likely sold - to be confirmed by vendor once things are finalized.
Just my opinion...