I'm with DieselDan. For a while I spread my purchases around several bike shops. After awhile I settled on the one that just happened to be closest to where I live. They are not the cheapest bike shop around but the have a good selection of stuff, have a good service department, and the owner hired a couple of guys to work the floor who were older than teenagers (I'm not knocking teenagers. I've got two of them. But sometimes they are not the most knowledgeable bike people) and seem to know their stuff. I've gotten to know them, and the owner, pretty well so that they all know me by name. Sometimes I buy stuff, sometimes I don't. At first I didn't spend a whole lot of money: tires, tubes, water bottles, socks, gloves, etc. Later on I bought some shoes, then a new set of wheels. Since I was comfortable with them, I decided when it was time to buy a bike I would use them since they were convenient and I could easily drop by if I had any problems.
When I was looking for a new bike (first new road bike in 20+ years), the owner let me test ride his Serotta Ottrott. When I asked if he wanted me to leave him a license number or something, he just said he knew me and wasn't worried. So I just went out and rode for an hour or so.
If I was a store owner and I had to choose between two potential customers, one of whom I knew never bought anything and another that I thought might really be interested in purchasing a bike, I think I would focus on the person I thought would spend their money. If I'm talking to one of the guys in the shop and someone walks in the door, I certainly understand when they stop talking to me, excuse themselves, and greet the new arrival. The shop isn't going to survive if people don't spend money there.