Really I always thought they were bots owned by GMs. I only held a convo with ONE 7-11 member in Payon and that freaked me out. I really don't mind them being there and don't see the point in all the whining everyone presents against them. If you don't like then don't buy from them. Same goes for PnP. I mean its all really common sense. Just ignore that they are there. They aren't causing any trouble, they aren't really affecting a lot of the prices unless you get competitive reselling things that can be bought in tool shops and NPC pet vendors.
Personally I've bought from them maybe four times and that was only because I was convinced by guildies to start stocking up on certain items. Other than that I never bother to even acknowledge their existence on the map.