My 155 was high mileage when I bought her. I did all the usual checks, you should be able to get a feeling for any car by doing this thoroughly regardless of mileage. The garage who sold it also had it's complete history (it was a fleet contract car) from the previous owners too.
A higher mileage car, provided those miles have been clocked up on open roads, should be a better buy than a low mileage city runner.
If in doubt walk away, there WILL BE another car to look at.
Don't forget the master key...