This is why Shampoo works as an anti-fog
When I used to live in North Dakota, hockey was a huge thing to do. People had those clear plastic lenses (i-tech) And they'd fog up when they'd play. So, if they didnt have time before the game to put anti-fog solution on, this is what they did.
They'd hit the bathroom and mix soap with water then apply a light light layer on the lens. This does the SAME thing as shampoo. Fog bulids on surfaces, but what the soap/shampoo does is leave a light film over the plastic so fog couldnt form on it. It's kinda like an invisible microscopic barrier that doesnt let fog collect.
That's WHY shampoo works, but I dont know if it's safe for paintball.