it takes less than an hour to roll it back. and because most are restored, there are no signs of condition. unless there is a serious paper trail of any service , there is really no proof other than one mans word to another. we all know its a 5 digit odometer, once it hits 99,9999 it goes back to 00,0000. I know here in CO , you can write any mileage you want on a title, or none at all. they do not come out to the vehicle to verify any odometer reading