I can answer this one...snakes can see red light they cannot see infrared light. The bulbs you buy in a pet store (specifically designed for reptiles) are coated on the inside with a chemical that removes all but the infrared spectrum of light (whats left is red in color)...
If you were to simply using a red party bulb or red plastic the snake could see the light just fine. Not to mention they can still see through any material regardless of color or coating just like you can (provided it is transparent...so they could still see you).
Hope this helps.