A friend and I on our first trip to Orlando, Florida were looking for bargains in the photo shops around International Drive... ...this was before we realised they were all tourist traps!
We entered one shop looking for a good deal on a speedlight. The salesman dismissed our enquiry by explaining that what we really wanted was an ultra-wideangle converter (no, I didn't get the relevance either!. He just happened to have some wonderful ones in stock at really marvellous prices.
My friend and I weren't convinced, so the salesman started to wax lyrical about the amazing build quality and, to demonstrate the build quality, took one out of the box and slammed it down hard several times on the counter. "See, great build!"
We explained at that point that we wouldn't be buying an ultra-wideangle converter from him or anything else for that matter. I think he seemed a little put out at our lack of enthusiasm but we were so busy leaving that it was difficult to tell!
At another shop a salesman tried to tell my friend that an EOS 300 was exactly the same as an EOS 500. A quick look through the respective finders showed 3 focus points on one and 7 on the other...
Ludicrous but true.