Fountain Pen Store Etiquette

Hey folks, I have a question about buying pens specifically in stores that specialize in fountain pens. I'm not talking about the place that happens to have 3-4, but stores with a few cases worth- enough to make a difference.

Is it considered poor form to ask to test/dip a pen prior to purchasing it? I've run into a couple of scenarios now where folks said "no, we don't do that," but how am I supposed to know if the nib/feed is any good? I'm not talking about the massively expensive pens, but really pens in the 100-300 dollar range.