I find the smaller the shop the better. More personal service and attention. The tradeoff of less choices is worth it. There are many duds out there just trying to move merch but I've had some very pleasant experiences with like minded people who love music. About a year ago I was demoing a pair of Amatis in NYC and through the entire demo the salesman was standing close by tapping his feet and enjoying the playlist. Very enjoyable hour with these folks.
Usually one knows very quickly if the person they're dealing with will be a good match. I've never let a mismatch get to the point where some salesman has the chance to talk downhill to me. Cheers