These spots I see not only on Oncidiinae Intergeneric Hybrids, I see on even the species of ... I am unsure what it is, one of my first orchid books says it is a fungus, but if it is, it is very minor, and does not spread... you can find the same spotting on other VERY thin leaved plants, like Grammatophyllum scriptum, Cyrtopodium species, Dedrobium finisterae, some Prosthechea and Epidendrum species... I never see the same spotting on thicker leaves, like Phalaenopsis or Cattleya...
I have a very rare Oncidium floridanum that has these spots sometimes... usually they occur when the bulb JUST finishes getting to a mature size, before it blooms... I never worry about it, because nothing has ever happened. I do watch it, because I would hate to lose this species...
Ascocentrums do have spotted leaves, and so does Oncidium stacyii... the pencil like leaves have slightly discolored spots, but are natural...
-Pat