Does reduced trimming trump centering?

[steve B]

I've seen a display of altered stamps that were good enough I couldn't spot the alterations. Those were miles ahead of any trimming I've seen.

I would be open to being tested. if someone sent a common or two, with or without known trimming to keep it from being just a hunt for what I would know is there, I believe I could find a trim nearly every time.

Could I do it in 30 seconds like the grading companies take? I'm not sure.

I would be open to similar tests for any alterations. Some of the borderline ones where some think it's altering some don't may in fact be undetectable some of the time. Like wiping off a wax stain.