Honestly, they will likely be like any other car with the same amount of miles. More miles will be more wear. In reality, most cars with say 35K miles on them still look dang near brand new after a wash and detail. Any gross wear items Tesla will take care of, but don't expect a higher mile car to be free from the usual rock chips (they will be touched up usually), etc. We picked up our 2013 CPO with about 45K miles on it and, cosmetically, it looked about the same as our 2012 Volvo XC60 (which we have owned since new) with a similar amount of miles on it. As with all cars, lower miles will likely have less wear. I did purposely pick up a slightly higher mileage car in order to get a loaded P85+ in the color combo I wanted. As I work from home, I knew we would be keeping the mileage low so higher initial miles didn't bother me (heck we have only put 5K more miles on it after 9 months and that includes 1500 miles in out of town trips).
I will say that I was a bit worried how the interior would look on our car, especially since we have the performance seats - I was concerned about the suede-like bolster areas....but it turned out to be a complete non-issue. Indeed, the seats overall seam to have worn very well.