I actually think most people post whatever they want, and I've certainly posted some "unfair" trades in my time. Always favoring the other player, because I needed certain goods at the time. And I don't really pay that much attention to the trade market in the guilds I'm leading now, because they're small, tight-knit groups that can be trusted to look out for each other. I have, however, been in larger guilds where there are players that post tremendously unfair (in their favor) trades, banking on the fact that others won't take the time to inspect them, due to the pages and pages of trades in that guild.
As far as finding a guild that follows your playing style, do what I did, found your own. I detest GvG, and most guilds will pursue it to some degree. So I founded my own guilds and made my own rules about GvG. Nobody is forced to join my guilds, but if they do, they follow my rules or move along.