Selling a caravan privately

During a long weekend away with 3 familys we watched a younger couple simular ages with myself with their kids set up the caravan,full awnin, and enjoy their hoilday on the second day during the evening i saw him trying to get the toilet casset back in place and lots of pages were flicking in the manual and scratcin of the head,so the 3 of us went over to offer some advice if he wanted it,The man was very happy to get advice as only things in the van was the water he had just bought the van second hand got all the auaq roll waste master thrown in the deal,the seller didnt bother to show him how any of it works just took his money and ran. After 15 mins and some silcone spray he had a crash course and was a happy camper gas workng water working heating on for the kids,awning pads finally attached to the awning and not just against the van and the toilet now working.

I just wouldnt sell anything with out showing them how to use it propperly.Has anyone else seen this happen or had it done to them?