I am in Arizona, but more than 100 miles from Scottsdale, and I have not heard of the dealer. There are a few people from that area on this list. It may help to put your post on the general discussion list.
I am curious about what scares you about a used car dealer of an MB in Arizona. I would think that you would prize cars from this state, because those from Phoenix and Tucson and surrounding areas are usually completely rust free.