AAMCO has a good reputation and as long as you're not in the ghetto or a location that would prevent people from being comfortable when they bring thier cars to you, then I think the signage will be an upside.
I'd go with high visibility signage over a nicer building with less signage any day. Personally, a lot of the places I go to for auto or motorcycle parts/service are places that I've driven by. Why? Easy, I already know how to get there.
Also, because of zoning most automotive repair shops are in industrial or light industrial areas. So, nobody is really going to be suprised. I'd almost rather go to a shop in a beat up old building than a new fancy facility. All I think about at the latter is how much more they have to charge to cover thier overhead.
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A thinker sees his own actions as experiments and questions--as attempts to find out something. Success and failure are for him answers above all.
Friedrich Nietzsche