1) If you walk into a store and don't specify a brand, they will direct you to the items on which they have the best margin. Likewise, they will direct you to the stuff that makes up volume. It is retail and that is a fact of life. People should just get over this inferiority complex stuff - you set yourself up to be directed to precisely those products.
2) Walking into VZW stores in AZ and asking for a Windows Phone or carrying one consistently demonstrated that staff were sufficiently knowledgeable and had no hesitation talking or selling the brand. The difference, of course, being I wasn't trying to test anyone so they talked to me about what I wanted.
3) Why would anyone want to waste their time going around to different carrier stores to test the staff about this sort of thing? If you do not work for Microsoft, what is the point? It is just a retail product line, not your child. I just cannot see why anyone would invest that much in an inanimate object.
4) Since you were obviously not buying anything, you also wasted other peoples' time. They are being paid to actually sell things and/or support paying customers. Does your desire to test stores outweigh their need to sell products and employ staff or justify potentially inconveniencing actual paying customers?
I am sorry but people really need to take a step back and think about what they are saying and doing. There is far too much being invested in a couple hundred dollars worth of phone and OS. This also treads a line that would get Microsoft or another retailer in trouble if they did it themselves