The most money-makingest question in music retail? That might not be grammatically correct, but you get what I am saying. The question is: “Can I get your expert opinion?”
I always have several taste tests in mind when I work the floor. Unsolicited demos, featuring two instruments (or amps, or effects) where all I want is for the customer to describe what they experience. And what make this magical is that you are giving them an experience, something they can only get in-person.
A powerful variation is to have them try two instruments that are essentially the same. I was at Gelb Music once and my demo was two 20” Sabian Memphis Ride cymbals. They looked the same, but they had subtle differences. When I asked drummers to try them both and tell me what they heard, it led to great conversations about sound, feel, and preferences.
Waiting for customers to come in and ask for something they already read about online is an expensive strategy.