They are not all affected by the same cause.
First two look rather benign. Unless it gets worse, I don't think it'll do much.
Plus, certain plants seem to have this as part of themselves. I'm not very familiar with bulbo. I only have one mini and it does not have any tiny black spots.
Dendrobium looks like it's got light burn. Do you grow this under very high light? If not, then it's obviously something else.
Paph leaf...browning part is a leaf rot. I would cut that big chunk off. Usually the end of it.
The strangely indented area is not related to the rot, but rather of different issue.
I have posted this before but no one was able to help. just many different guesses. lol
So far, I have found this indentation on the leaves harmless.
Phrag leaf- I assume the two pictures are of the same leaf only time lapsed? It's a bacterial brown rot. Unless it is getting bigger, it looks like it pretty much dried up on its own. I would seal up that spot with clear nail polish or something in case it continues to serve as a point of future disease spread.
Yellowing plant, check the roots. Probably gone.
The rest looks like mite or virus or various other issues.
The last one, are those black area elevated??
I see that quite often on cattleyas. seems like just ugly "skin" issues rather than disease.
My opinions so far.