I think that instead of showing the name of the retainer selling the items, it should show the name of the player who owns the retainer instead. So, for me, anything I sell would be sold by "Aislin Delhir", rather than showing the name of one of my retainers.
The positives would be that if someone would like to try to make a deal with the person selling items (ex., "hey, I'd like to buy X item, but I'd prefer to pay a little less - I would like to buy a lot of them, though!").
The negatives would be you could harass the person selling stuff, but if people are being harassing, you can just blacklist and/or report them. I personally don't see this as a big deal.
If the negatives are too much, I'd rather it just don't show a name at all. Just show me the price and the quantity and that's it. Why...? Honestly, the things people name retainers is pretty awful. I understand some player names are awful too, but with the retainers it really just amps up the bad.
Like, there's a retainer I'm looking at now called "Tigolbitties". Thanks, guy, and thanks, SE, for making me look at that. So clever.
Having the retainer name just isn't useful information. The best it can possibly do is annoy me by being a stupid and/or offensive name. Not exactly a plus in my book.