I believe that player owned vendors simply shouldn't have names that are publicly displayed. (an alternative might be to have them all read Private Vendor) Instead, they should have names that are only displayed in the chat window and NEVER overhead. There should also be a way for players that own the vendors to write up something about what they're selling (kind of like the signs have). So if you hover over them they show the writing but if you never hover over them they don't. I believe this would take care of all of the annoying use cases, and keep the player owned vendors back into the shadows just a step from where they are now (which is directly in your face). Also, making the names NOT display EVER would probably be a good thing for system usage and help performance in towns where there are a lot of these vendors.