Not a bad plan, especially in public or in mixed company. But in the grocery store I never see anyone younger than me buying produce and raw food. They go straight for the trendy upsell items; organic boxed/frozen foods, power beverages and the like. I stay out of those aisles.
The only other stores I hang out in sell things that go "bang". Not many young trendoids come in, and when they do they are usually good for some laughs.
I ignore every one under the age of 60.
Actually, that's the exception when I'm in public. I won't horn in on a shop owner instructing someone but I have found 100% of the young types in those establishments to be respectful, polite and eager for knowledge.
Sort of like Henry Bowman in "Unintended Consequences".