I've only ever flown with one guy who padded his hours, and he did it with great vigour.
He was an F/O with me when I used to fly a Citation, and I'm pretty sure he started to log the flight time from when we left the house to go to the airport.
He ended up in Ansett as an A-320 F/O, but after the airline's demise he isn't in aviation any more.
His lack of real hours showed in his handling skills of the Citation (very easy plane to fly) when he first got in it, but he picked up to a reasonable standard after some time in it.