Your right and I think one of the big reasons why is; When buyers see domains for sale here that receive little to no interest, They assume the name has no value, After all this is domain forum where the pros know best right?, If the pro's aren't bidding on it, perhaps I shouldn't either.
this has been happening for quite some time now.
i have seen several of my names listed on namejet that had bids, and like others, i got no offers for it here.
but in most cases, i'd rather let the name drop and somebody else win it for $69, than sell it for less.
i do think there is some truth to "assumption of value by others", as someone may want to bid on a domain, but won't make an offer unless another member does first.
it's almost the same with giving appraisals, many don't want to be the first to comment.
then again, the buyers/bidders on nj, gd, snap, pool etc, may have missed the domain when it was posted for sale prior to expiring or they may not be members here or at other forums where you post.
we can't just assume that our domain didn't sell because it got no interest here, maybe we just didn't put it in front of enough eyes.