Red is often associated with anger and whatnot because it gets people worked up.  Obviously, for all of these, the effects are very mild.  However, there can be significant impacts from mild results.  I couldn’t find it anywhere, so I didn’t include it in the comic since I couldn’t verify the credibility of the story, but supposedly there was a bridge that people would regularly commit suicide off of until it was painted blue, at which point the number of suicides dropped to zero.  Another story that I couldn’t find was that a not particularly great football team painted the locker room of the away team pink and would win most of their homes games, supposedly as a result.  Pink, for anyone that couldn’t guess, is a big testosterone killer, so that was the logic behind it.