When I think of spotting redials, it always reminds me our two boarder collie sheepdogs, we had when I was growing up. Bear with me!
To me they looked so ridiculously different I couldn’t understand how my friends couldn’t tel them apart. “Which one is that?” I’d hear every time mates came over. As I saw them every day I knew every little detail, who was slightly larger, thicker fur, slimmer nose etc. to my mates they were two black and white dogs.
It’s similar with redials (imo). When you look at them frequently, 95% are obvious from a cursory glance. Because we know the exact thickness of the font, the serifs, the length of the minute markers etc. but, from a less experienced perspective, I get (and I can recall when I was starting out) how it’s really hard to tell when you don’t yet have your eye in. Yes reading articles is invaluable but for me, you need to look at tens or hundreds of known original dials so you understand what they should look like. Then over time, redials jump out like a fluffy sheepdog.