In September 2017 Ebay seller alphaventures from Farmington, Michigan in the USA was selling this fake or sample San Marino trailer plate.
This plate has many things wrong with it: The registration should be blue, the small red R should be full size and, as of 2016, the population of San Marino was 33300 making it impossible for there to be 35600 trailers as the registrations started at R900. Other approximately 20 year old samples are similar to this one with the tiny red R.
Although it looks dirty and used and looks like it could be genuine, always check that a plate is close to that particular country’s genuine plates. There are several websites like Francoplaque and Plateshack that have pictures of genuine plates. For those who can join, the forum http://www.avto-nomer.ru has by far the best collection of photos of genuine plates on vehicles anywhere on the web but the forum is Russian language.