Shack, one of the smart guys on our course, ex-ranker, had PLASTIC collars. They looked the real deal even down to the pattern. The give away was the sheen stayed on whereas it wore off on the starched collars.
Which leads nicely to the BK story of the airman who put a note with his laundry saying "a little less starch on the collars please" His laundry was (allegedly) returned with a note requesting "a little less sh1t on the underpants please"