Sight can be tricky--I have seen a number of pre-82 pennies with good mint luster intact (piggy bank dumpings), and a lot of the newer cents which are downright ugly.
I have found, however, that when a copper cent bounces off the hardwood table it rings, and the zinc ones sound flat. Compare, and I think you'll find it works very well.
I can spot ‘em pretty quick...at least for the first 20 or so rolls..LOL. Then my eyes go glurky.
Yes, I agree, there are large numbers of 1980 pennies and some from the 70’s in unbelievable condition, for some reason. Mainly that one year, 1980. And yes, there are recent ones that look like corroded turds, just rotten.
I also notice that the 82’s and earlier have a significantly better strike. I usually pick out the clearly brown (good) ones that you can pick out almost immediately, then go back and just work off the depth of the strike on the date, without actually reading the date.
I just gather all the 1982s and weigh them later.
Nobody gonna get rich off this exercise, that’s a certainty.
The only blessing (for me) is that I have a super good coin counting machine, a Cummins Jetsort which I bought for no good reason except it was cheap, and it counts out the good and bad rolls pretty quickly.