I know you asked about the red eyes, but since I don't know what causes it, I'll throw you some advice on how I avoid "looking high". I avoid looking high by...LOOKING HIGH! Seriously, since I was like 13 years old I've looked high every day...even for the 2 years that I was completely clean. Looking stoned all the time keeps you from looking stoned when you are...it's great. Kinda like ninja tactics or some shit...