I never liked any dealer advertising on my cars (pot metal, stickers or license plate frames) so I always removed them. However, my wife bought a used 911 from Vasek Polak in spring of '99 from the old Hermosa Beach dealership location (the car was originally sold from that dealership when new in 86). It had a nice metal license plate frames but I removed them given my general distaste for those things and mounted them on the garage wall. Shortly after her purchase, I guess his estate sold the dealership and it moved a few miles south on PCH and changed its name to Pacific Porsche. Given Vasek’s Porsche history, I’ve since come around to liking that particular frame and have put them back on the car.
I think if the original dealership had interesting history with the brand (Vasek Polak, Tasca, etc), a badge of some sort lends something interesting to the car if that was where it was originally sold.