The vintage guitar board I used to frequent operates in a similar manner.
A buyer (or just a curious poster) will post a link to an e-bay guitar, or somewhat less rarely a dealer guitar or one posted on the site's Buy and Sell classifieds.

Sometimes the question is "Whadya think?" sometimes it's "Does the pickguard look original or didn't they use those tuners in 1943, not 1937?"

Usually a couple of members will take a stab, and then later on one of the "big guns" a guy who can spot a major internal structural problem from a tiny wrinkle near the fingerboard, or a refinish just by examining the neck joint.

It works pretty well, with few ruffled feathers, but the key is knowing which posters really know their stuff and which don't.

That said, I don't think anyone feels the need to "police" classifieds except in the case of outright fraud such as someone hijacking an account or dealer photos and trying to make a quick score on a guitar they don't own.

best
Allen