I think trying to educate a bank teller (or anyone) on the finer points of coin-roll hunting probably falls into the category of being an incredible bore. Most people just aren't that interested, in my experience. I find that saying, "I love coins and I like looking for interesting ones to keep" (which is 100-percent true in my case) is all most people who ask want to hear. Maybe even a little too much. They might follow up with "that's cool, my grandmother gave me some coins once" or something like that, but that does it. It bores them.
It reminds me once of a guy I met once who was into little radio-controlled 4x4 vehicles. He was at a table with some friends of mine so I asked a couple of polite questions about this when he brought it up. He unloaded on me. He "educated" me about how the market for certain radio-controlled trucks was exploding among collectors, but you could get really ripped off if you didn't know to look for these particular things, and that only two manufacturers could be trusted for these certain parts, and that knock-offs were easy to spot except the ones that weren't and while they were excellent to play with they certainly wouldn't be worth anything to a real collector, and...it was stultifying. I was praying for the dude to stop.
He was certain that other people had to be as interested--fascinated--in that hobby as he was, whereas I was in the vast majority of humans who, sadly, were not interested in it at all (except as a point of sociological curiosity, maybe). While he was talking, after a while, I just felt the minutes of my life dripping away, wondering how a grown man could turn something like toy trucks into such a seemingly collosal waste of time. And I truly, honestly did not care that some of those trucks were supposedly worth thousands of dollars, which was a very big part of the appeal to him. God knows what kind of dangerous "insider" info he gave me. He could have even given me a little cheat-sheet pamphlet to take to flea markets. Which I would have thrown away. Becuase, to me, they were...toy trucks. With knobby tires. And batteries. Vroooom! Thanks, that's all now.
Sure, any sentiment that his totally-absorbing hobby might be a silly waste of time was certainly a hypocritical judgment, given the hobbies I've had before and have now, but what can I say? I don't like what he likes. Toy trucks just don't mean anything to me. I'm glad he gets so much pleasure out of them. The world takes all kinds.
I'm pretty sure the look on my face was the same as you'd find on most bank tellers who were being kindly informed, "Now, listen closely cause this is important: You've got your 90-percent halves and your 40-percent halves, which can look similiar to the untrained eye but don't be fooled..."