After looking at many nice lower mileage Benz's (and from getting burned a couple of times) I think an average mileage car WITH service history so you can determine if some or all of those problems have been dealt with is the way to go. If dealing with an MB dealer - only that dealer will have repair records of what has been done at that specific dealer. Their system does not contain repair work performed at other dealers.
The dealer can print you a copy of those records and explain them to you (sometimes they use codes). Any dealer that is worth anything will contact any previous owners and ask them if it is o.k. for them to give you info. about the car - they will also mark out any information about the previous owner and costs that are on the repair printout.
I just did this at the local dealer two days ago. If the salesman does not want to help with this either ask to see the service representative or walk away but not before telling him why you are NOT going to consider purchasing that vehicle from him.