Notice that the car he'd originally sold that the buyer later found out had been written off, he put it back on and sold it with a little "insurance claim but repaired good condition" on the ad.
Mistakes can be made though.
When I was trying to sell one of my old cars one potential buyer ran a full HPI check which showed up with a supposed mileage irregularity, so he claimed I was trying to scam him. But the reason the "mileage irregularity" had been flagged up was because the car covered a large number of miles in one year compared to other years, so had jumped up in between services/MOTs when the mileage had been recorded.
If the mileage had gone down, then that would be something to worry about, but the mileage going up was normal (if quite high) usage.
