I have that blotchy look off and on, probably because I can't ever be sure of spraying every orchid with the right amount of fertilizer. But it does seem to just come and go, and not leave any lasting damage.
I now add a tablespoon of magnesium every time I spray my orchids through the rainy season and they do look much better this year than last. I think . . .
Wish they could talk to us a bit more clearly, huh?