Hello fabulous orchid growers

Ok, this is kind of a general question. I have read the sticky on diseases, but I still feel like I can't tell when something on my orchids is bad and when its just a little nick or tear or dirt or anything

How do you tell when something is a disease, or when something is completely benign? I know fungi and bacterial ailments will feel soft or moist (right?), so I don't think I have any of those. But I do have little black marks on some of my orchids leaves. They have never seemed to spread, so I assume they are ok....
I know there is no one-line answer, but after reading so many things on orchid diseases I am feeling a little confuzzled (confused and puzzled

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