If it is fungal, it may not be the type of fungus that can be wiped off (powdery mildew/sooty mold/some forms of rust). You may have to pull out the big guns and treat with chemicals.

I am more inclined to say that, since it doesn't wipe off, and you have no pests that would create honeydew for mold to feed on, it is NOT a fungal issue. The other types of fungus (not powdery/sooty) normally create large, black spherical splotches on the leaves.

Honestly, it looks like humidity or airflow damage. With no air circulating, and if you have higher humidity, you set up a perfect breeding ground for fungi, bacteria, or just strange spots (humidity spots?). The worst thing to do is turn off fans, if you will be away, unless you have someone who will turn them on/off for you while you are gone. Airflow is very important to most indoor plants.

It is NOT sunburn, which appears as a thick, white scar or bleaching of the leaves, like the pics below:

If it is only a couple of leaves that are affected, you should remove them ASAP, in case fungi or bacteria are present. If things don't improve, you might want to treat with systemic antifungals/bactericidals.

Thanks aurorawa. Ugh, I could kick my husband in the arse. He turns everything off and unplugs most things in the house when we're gone for a few days. I love this Hoya. I will pull out the big guns (lol) and use Heritage. I also cut off the nasty looking leaves. Thanks again.

I agree. ...high humidity with no air flow, will deplete the oxygen in your growing area leading to fungal infections

I had it hanging in my kitchen window with several other Hoyas and only this one had a few leaves like this. Kinda strange. That's why I wondered if the soapy water w/ a little oil had something to do with it.

Was it warm and humid in Raleigh this past weekend Jimmy? I was in CT where it was chilly and raining on and off.

Can leaves get something like clogged pores??