There are many traditional fairy tales that use the color red to signify evil and danger. The Evil Queen gives Snow White a poisonous red apple. The deathly red dancing slippers already mentioned. Poor Dorothy who puts her self and her friends in danger by wearing the Ruby Slippers. There are also those poisonous Red Poppies. This may be a subliminal reference to blood and fire and may also be used to instill in young children an aversion to unfamiliar things colored red.
Poison oak and Ivy leaves turn a brilliant scarlet in the autumn.
Many red berries like climbing nightshade are toxic.
Red Baneberry, holly berries and yew berries will make the eater sick. The stunningly attractive Fly Agaric mushroom is deadly.
Red is commonly used in movies to foreshadow that something bad is about to happen, for example, domed character will walk past a red door that came out of nowhere. I was telling Tessa about this use of red as we were watching Jaws. As if to make my point, the little boy at the beginning who is about to be eaten by the shark, walks across the beach in a …you guessed it…red bathing suit. If you start looking for instances of red at climatic moments in movies you’ll be surprised at how often it’s used.
Darth Vader’s light-saber was red. The good guys had blue energy. In the Sixth Sense the color red is on screen only when dead people are in the scene. (I had that movie pegged within minutes. I saw it with someone who had already seen it and told me I was going to love it. I turned to him during the first seen with Bruce Willis and said “He’s dead too right?” Lame!