It depends on the game settings they were using. I like my games to play the way they were intended. Upon getting a pin I check it. If I find difficulty or the amount of balls given is different than default settings than I erase all scores.
For instance I bought this Hobbit machine. I wasnt going to erase the scores untill I noticed many mode settings were set to easy, no tilt-bob installed and the ball limit was set to 5. No thanks! Im not huge on competing against scores which were unnaturally high in the first place.