Ironically Mountain Dew residue was one of the things I was washing off with my water and soap method. Maybe that is why they came out as shiny after I washed all the gunk off.
Dunking pennies in vinegar with some salt sprinkled in, then rinsing them in cold water, will get most of 'em nice and shiny. But easier just to get a new roll from the bank.
You must’ve been a teller a loooooong time ago: Large denominations of United States currency - Wikipedia
They end up in circulation every once in a rare while. I got two during the three years I was a teller, just when they happened to come into the Chicago Federal Reserve, and the only reason I got them was due to that particular customer’s request.