Blu-rays and scratches

[DukeTogo84]

So I've recently been buying a lot of used Blu-rays and while most have worked perfectly fine some, have had issues.

What's weird though is that I have a couple of discs that have huge scratches on them, and they play perfectly fine. However, there are a few discs that have one or two TINY scratches and the disc barely plays. I'm no pro on how these discs are made, but just wondering why this might happen?

I would figure the larger scratches would be the ones that don't work, while a few with tiny scratches tend to stop working.