I don’t think I would recommend my cat’s crap. Of course it might help remind you not to try to breathe through your nose. ;)
I take a small bottle and fill about 1/2 full of baby shampoo then add less than half that much glycerine. Use a couple drops of this solution and smear around the mask then rinse lightly. That seems to help a bunch for me.
If all else fails under water, or if I forget my lens juice and it fogs a bit, I let just a tiny bit of water into my mask and roll it around a bit to let it rinse off the fog. That very small amount of water doesn’t normally have to be removed, but my mask has a nose valve so if I have to get that out it is no problem.