when looking for a glass shop in the past,,i've always tried to find the place that looks like its been around for a long time,,same with the people that work there. look for old timers. they'll take the time to do it right and they know all the "tricks". if theres a buncha kids workin there they probably dont know a piece of glass from a piece of a**.
when it comes to your windows you definitely want them done right the first time.