What is the question specifically? I'm trying to see something untoward in the pictured plant.

I don't know why the description doesn't work... I have had this same dendrobium (super model) for about half a year now and overtime, there has been this odd black powder that has grown underneath the leaf where it connects to the rest of the orchid. I don't know what it is and I wanna know.

If it is indeed powdery, and spreading, then it could be a form of powdery mildew, or just a mold. Not too sure, it may be a rust though. Try using a fungicide. Not too sure.

Thanks, I took a softer approach and used isopropyl alcohol with a cotton swab ^^