Smith's lenses have had a known problem with the breather valve (white dot on near upper corner) on their lenses for a while. Sometimes the valve gets clogged, or will let moisture in to become trapped. I believe this is on the ventilator series of lenses. Ill fitting goggles with gaps usually won't fog because they allow additional air circulation which also means they aren't keeping wind off the eyes. If ill fitting goggles let your breath in around nose, under eyes etc, they will fog but only on the inside. Goggles with the vents/vent foam blocked will cause fogging on the inside of the goggles, but not between the lenses. Fog between the lenses indicates the seal has become compromised and allows moisture in. Some seals are more durable than others, but heat, flexing and moisture will weaken them.
Last edited by bseracka; 12-31-2012 at 05:35 PM.