I find this problem with some helmets but not so much others. The latest helmet I bought is a bastard for it. I put it down to the interior air channel design and the pad layout. By shifting the pads around and adding some others (doesn't everybody keep those spare pads from other helmets just in case?) I now have a thick band around the bottom which is more or less acting like a sweat band. Basically I was trying to do the same thing as that GUTR and channel the seat away from my eyes and forehead. I'd almost given up and was going to buy a new helmet, or even a new bike!