Comments are fine, even just a ‘nice bass’ doesn’t cause any harm, it just bumps the thread. Don’t know why anyone would want to ban comments like that, nobody is making you read them and often some really interesting discussions can evolve.
Comments on price are of course best kept private, the general rule being people can sell for whatever they like as its theirs - obviously any fraudulent or proper piss taking can and should be reported but I don’t know that I’ve ever seen that happen.