The military surplus suits, or as Grizzlyman referred to them, MOPP suits (that stood for Mission Oriented Protective Posture), are loaded with loose carbon to act as a filtering barrier between aperson's skinand an environment contaminated by a chemical warfare agent (nerve, blood, blister agents). Needless to say, there's no comparison in the amounts of carbon in those suits and a Scentlok/Scentblocker suit.
The downside, as I said, the carbon is loose and not bonded with the material. You will turn black when you sweat. Also, they're extremely hot in a warm environment. I remember spendingall day inthose things wearing a gas mask during battle drills. One word described it.... miserable.
I've never invested in carbon clothing, but in cold weather, they'd probably be an effective, inexpensive way to go.