But that's the thing. I usually don't go into a store looking for oddball stuff. For photo stuff, I'm just looking for the staples. Things lik D-76, Stop Bath, Fixer, HCA and PhotoFlo. My store usually stocks a selection of Ilford papers and at least one brand of film in 400 and 100 ISO. About three times per year, at the beginning of every school term, they'll stock up on supplies. Toward the end of the term, their supplies dwindle. These are things to be expected in any retail business. These are not the things that bother me.
When I go shopping, I'll usually have a certain brand or product in mind. I often look for it on the internet, first, and see if any local stores carry that item or at least that brand or a similar product line. At this point, I believe it is reasonable to go to a store and ask for a specific product. At this point, I believe it is reasonable to complain when the store doesn't have what you want. How else can a store know what products the customers want to buy if they don't tell the staff what they are looking for and when they don't complain (with reasonable manners) when they don't have what people want?
On the other hand, if I go to the store and they have what I'm looking for, it is reasonalbe for the salesman to expect me to buy.
If the price isn't too expensive, compared to other stores and if you take internet pricing into account (product price + shipping/tax + reasonable retail markup) I, most often, buy on the spot. Why would any half-intelligent person spend the gas money, brave the traffic and generally withstand the hassle of going to the mall if he didn't intend to buy something?
The exception to that would be if you are already in the store and you ask an off-the-cuff question for a product.
If I was leaving the store and, on the way out, I asked, "Hey, do you have any Tri-X?" I wouldn't expect the guy to jump up and get it right now. If he answered, "We're all out but our order comes in next week," I'd be fine with that.
I guess the bottom line is that it's all about context. I understand that. However, the retail trade is all about selling customers the products they want to buy at the prices they can afford to pay. When a store consistently doesn't meet expectations, they won't have much business... at least not MY business!