I once decided to try life as a blonde. (I know, but my appearance is already improbable: how much more unlikely would that hue be?)
I quickly discovered, in order:
1. I don't react well to the chemicals used in hair coloring. It wasn't so much scalp trouble as the stench: I spent half the time in the chair desperately trying to either get out of it or rotate to the sink, and finally just asked for a bucket on standby. This has turned out to be a more or less permanent issue and I usually have to clear the room when someone's applying a treatment.
2. Red to yellow? Is not the easiest or quickest transition in the colorist lexicon. Things were done to my hair which are outlawed in most Third World nations for cruelty. I found a call to Amnesty International on my phone: I'm pretty sure that was made by the backfall...
3. The end results were -- "blackmail material" is a good choice here. Or blondemail material. Let's just say that all the pictures I know about have been destroyed and if there's any others, I will learn about them the next time someone needs a ride to the airport or worse, up through and including body removal.
4. The transition back (which was allowed to take place naturally because one extended toxin exposure was enough) included hues only seen in sunsets over leaking nuclear power plants.
5. I did not have more fun.