The big problem, as I see it, is this. Seller asks for £X. A potential buyer likes the car and is willing to pay £X but, by the time people have finished putting their tuppence worth in, buyer feels a bit silly and either pulls out of the sale or doesn't even bother to contact the seller.
When I bought my daewoo, and my snotmobile, I posted up the pics and details beforehand. I was, of course, greeted with howls of derision. This made not a jot of different to me, because I am, in the main, a person who makes his own decisions and then stands or falls by them. But I can see it would make a big difference to some folk.
If an eBay link is posted up and people genuinely want to save the potential buyer from himself, then that's fair enough. No one wants to see anyone taken for a mug. But when a fellow member puts his omega up for sale, then questions can be asked of him regarding things like mileage, service history etc., but unhelpful, pointless comments should be frowned upon. It can only upset the seller and, possibly, a potential buyer.
We all know our omegas, or should do by now, so, unless a potential buyer asks you by pm for your opinion........shut it.