At the trailer company i work, we sold a couple of damaged trailers (mostly accident damage)
As long as they come with some paperwork, they are worth at least a 100 Euro...
I dont know why but afterwards i wondered if these trailers paperwork and VIN number would be stamped into some stolen trailer ... ???
Anyways, these guys could also just use the trailers identification for a home built trailer, or to certify an older trailer, as trailers from 750-3500 kg didnt have to be registered untill 3 years ago.