You could ask to have the fragrance sprayed on your skin, then mention that you wish to see how it develops.
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Okay, back for a bit. Had to feed my family supper.
Most upscale stores around here have the tester bottles accessible to the public for testing. It is quite proper to test for yourself, on paper and/or on skin. I've never been told not to test the fragrances, or to limit myself to any given number. The assumption seems to be that customers will be sensible.
If the bottle is behind the counter, by all means request it so that you can spray it on yourself. If the sales associate sprays it on paper, it may just be that they were trained to do that. I would accept the paper strip, smell it; then, if I liked it, would ask to try it on skin.
Depending on the sales associate, I might have a conversation with them about the scent, my impressions etc. Or even about what fragrances they like. If they seem to like fragrances (as opposed to its just being a job for them) I might even tell them about Basenotes, invite them to visit the website.
I never feel pressured to buy anything on the spot. It isn't really expected. My usual statement is that I would like to see how it develops on my skin. I might ask for a sample to take with me for further testing the next day. Some stores make up samples for customers on request-- Nordstrom and Sephora do this. I don't generally ask for more than 3 or so.