As an etymology geek, I'm fascinated by how the original name (Fairy Floss) came to be prevalent in my home country of Australia, while Cotton Candy predominates worldwide.
Great question. I didn't come across any explanation for this, but I did dig up some other names for cotton candy around the world:
France: Barbe a papa ("Papa's beard")
Greece: μαλλιά γριά του ("old lady's hair")
Great Britain: Candy floss
Wow! In Gujarati it's also called "old lady's hair".
I can't say with absolute certainty that it's called this across the entire country, but in my part of Sweden it's called "spunnet socker", which translates to "spun sugar". Certainly seems more appetizing than beard or hair at least. :)
In Dutch, we switch those words, and call it "suikerspin", which could be translated as "Sugar Spider" or "Spun Sugar", I suppose.
In Denmark it's called candy floss. Guess the Danes couldn't decide on which name to use.
I saw irony in the title at first, and conspiracy on second thought.