Ask to see the service history.
I was looking for a car for the wife a short while back and went to look at a buzz box. I asked to look at the books, owner said no worries, that it had a full service history when he bought it, and that after that his mate down the road looked after it for him so there were no stamps in the book but he assured me the car had been serviced properly and there were receipts for filters and oil etc in the book. The last official service was done almost 3 years prior, and showed the k's that were on it at the time. I then looked over at the odometer, at it showed that less than 1,500k's had been put on the car in the ~3 years since the last official service but enough receipts for 4 or 5 services.
"How many times exactly did you get the car serviced, since it's only done 1,500k's in the time you've owned it?"
"Didn't you tell me before that your wife uses this car every day to get to work?"
Mumble mumble duck weave mumble...
No idea how many k's it had really done, but a pretty bloody good idea that it had been wound back!
Justin.