If it is used at all there will be some marks and scratches. That is a given, but you can tell something that has had a lot of use or that has been driven on concrete or rocky areas vs a dirt or clay track as a normal day out.

But, yes, the driveline is the major make or break on it... worn out cups or bent shafts do not have to be a deal breaker but your price should reflect condition. If they let the bearings seize of run to excessive play that is sign of maintenance issues and you should be wary then as well.