Labelling of former car hire

Hello, in my search for a second-hand car I always come across offered former car rental cars. These are unfortunately only difficult to recognize as such. An example of last weekend: On my direct question, whether the Renault Mégane was a former car rental, this was expressly denied by the offering Renault dealer. Rather, the car had been admitted to Renault AG, which only a factory member could be considered a pre-user. However, I discovered a sticker from the Hertz company on the inside of the driver’s sun visor. The dealer pointed out that it was quite possible for Renault to transfer his vehicles to car rental companies. I watched as soon as possible to disappear from the dealer’s yard. Therefore, my question: Is it up to a dealer (apart from the obligation to tell the truth) to mark a former car rental as such so that this even without direct demand?