Wherever I go in eastern Canada and the US, I've found three octane options at the gas pump. Bronze, Silver, Gold. 87, 89, 91. Regular, Plus, Premium. Western states add a discount option, 85; I'm not sure whether they're stingy or whether conditions allow a cooler fuel. I know 85 is throughout Utah, but I'm sure I've seen it elsewhere.
Just about everywhere, the button for the inexpensive, low-octane option is on the left, with the higher priced options further to the right. Except, every once in a while, you'll come across a station where they put the low octane in the middle, and the medium octane on the left.
I don't think it's an accident, or a local tradition of reading out from the middle. I think because the owner of that station believes that tricking people into buying a higher octane than the customer actually wants, is more important than serving the customer honestly.
It can't make much of a difference. Regular customers know which button is which, and buy the grade of fuel they intended to buy. Even if the profit margin is better on the higher grade, is it really worth it? Perhaps the supplier imposes some quota, or varying price levels based on quantity. That last one sounds most likely to me; a small increase in the quantity of medium grade fuel leads to a lower price on a large quantity delivered to the station.
But a business that sets out to trick customers will probably cheat them, as well. It will probably stiff the employees, use sub-standard tools and supplies. The product or service you get from them may look as good as any competitor, when it's installed, but how about months or years later?
Contrast that with the people we admire, David Strobist Hobby, Chase Jarvis and others who view photography as not just a business but a profession. They'll pursue someone who tries to rip them off, but they'll go out of their way to ensure the client is satisfied with the results.
It's the little things that enable you to identify one from the other. Not all companies can afford snazzy locations, but if you're nervous about sitting on their chairs, they may skimp on the important stuff, too. Nothing wrong with plain and simple, but the attitude toward the toilets, the secretary or tool and supply storage may indicate the attitude toward the product, as well.