But why can't you just ask for what you want without people automatically assuming you're stupid? If you care that strangers think you're dumb you have to adjust your behavior a lot and some people would rather just be genuine. Besides, the easiest way to not look stupid is to make up a reason that sounds reasonable (i.e. lying) to get what you want. This is what many (most?) people do. If they want the Apple computer that comes in the smallest package they'll make up a BS reason (i.e. flight luggage restrictions) in order to seem reasonable to the stranger who works at Apple.

The question is really what kind of person do you want to be? Do you want a person who habitually lies about unimportant stuff in order to accomplish goals? Do you want to be a person who is genuine but gets unfairly judged by strangers? Or do you want to be a person who justifies themselves to strangers in order to avoid getting judged?

If you think lying is wrong and seeking the approval of strangers is a bad habit only one option remains.