I don't have problems with my binos fogging up, just my glasses. What a pain! Rain-X helps.
I'll tell you, for those of us who wear glasses, it is a love-hate relationship for sure. I'm glad I can see, but when I work up a sweat, and I can sweat doing nothing but standing in the sun, I feel like I spend more time wiping off my glasses than any other single thing I do while I'm trying to hunt! It's a lot of motion, too.
I finally got a Halo Sweatband to wear under my cap (looks like a dew rag and makes me look like a biker, but so what). It has a hidden seal on the forehead that directs the sweat down the side of my face instead of letting it flow into my eyes and onto my glasses.
No more wiping glasses every two minutes, no more bleary eyes stinging from salt from morning to night, which for anyone who knows what I'm talking about, is like a gift from heaven.