I have only had my VIN checked one time. It was back in the 70's, and I was driving my 1966 Shelby GT350 at a normal speed on a rural backroad. Maybe I attracted him because the car was White with two big Blue racing stripes (and open headers).
I had installed new headers at home, but could not get the collectors to mate up to the exhaust. So, at 7:00AM the next morning, I thought I'd cautiously drive to a local shop to have the new collectors welded up. I was driving as quietly as I could (with open headers)
Officer friendly was sitting in a school parking lot, and must have heard me coming (how could he not?). He pulled me over, and I explained to him that I was on my way to get the exhaust system repaired. He started looking at the dash to compare my Registration to the car's VIN - that's when I opened the hood to show him that in 1966, cars didn't have their VIN on the dash, it was under the hood, stamped in the fender apron. He said "Oh, you must have to do this pretty often, eh?" I bit my tongue and was silent. He issued me a "fix-it" ticket, I went on to the shop to have the exhaust welded up, then I drove to the local Ohio State Highway Patrol Post to have it inspected, and the ticket discarded.
I have a great deal of respect for the job police officers do...they put their lives on the line every day. Most of them I've met (even the ones who DID write me) have been pretty good guys.
Jeff