This type of issue has come up before and I am not sure that the advice give above is correct, or at least is incomplete.
Naming and shaming amongst FPN members is not permitted for sure, and I don't think is regarded as acceptable even in the wider community on the basis that an accusation is made and the members only here one side of it, as in 'I sent my Parker 51 to Dodgy Repair Man and he did a terrible job, don't use him.'
In the past there have been badly described ebay ads and even ads that have been intent on deception and further information on the seller and the ad was permitted and, presumably, within the rules of FPN.
I recall that one Moderator even invited an unscrupulous ebay seller to respond to comments made about her ad on ebay, what followed was abuse, (abuse isn't actually the correct word, threats would be closer), to all concerned. I was promised a visit from her boxer son because I had questionned the idea that a Parker 51 with a broken clip was not a rare Military cap.
As a halfway house, you could post a link to the ad perhaps, as I have done with ebay ads for pens which claim to be Parkers, they may have flown over the Parker factory on their way from China but that is about all.
With regard to your final question 'Is there a thread in FPN where complaints and praise is found?', there is no appropriate thread and it sounds like a potential minefield, best left alone.
Edited by Parkette, 22 June 2020 - 16:42.