Tifosis do fog if they're close to your eyes. I have one set I like a lot - it does fine if I'm moving >10mph, but it fogs on slow climbs.

My NATIVE sunglasses do not fog, however. No matter how slow I'm going. It's quite remarkable, as I didn't see any mention of any special anti-fog. They might fit differently, but they feel extremely similar to my Tifosis.

Price may reflect something though. Tifosi = $40. Natives = $90+