That's an extremely flawed argument. If you can't explain it to a layman then you don't understand it. If you can't tell whether it's a gap or a fracture -- you can't get a conviction.
Interestingly there's an area of psychology called Naturalistic Decision Making which studies how experts make decisions that they can't explain. (Example: a firefighter may be able to pinpoint where a fire is before they enter a house and see it.)
"It just looks like it" is not a valid reason.