When you visually compare two hashes, how many digits do you check?

The strings hashed below are "retr0id_18b1f814a8e2d9c4fb9c" and "retr0id_1253dea672ebfa240e94", if you want to check for yourself.
@retr0id would probably catch me out if I was tired but the "shape" of the characters in the middle is the biggest giveaway here
@retr0id it'd be cool to see collisions that rely upon common character mutations (d/b, 3/8, 5/6, a/e/c) as a way to make it harder to spot that the middle part is wrong.
@gsuberland Yeah that's what I'm looking into next, I think I've come up with an efficient way of doing it