All of my non-production machines have emojis in PS1 somewhere. It sounds ridiculous, but I know that if I see a cheeseburger or a burrito I'm not about to completely mess everything up. Silly terminal = silly data that I can obliterate.
I think I'd rather make the production systems stand out, and add the emojis there. My prompts have a red background, but emoji prompts just tickle me, somehow.
ha! I do the same thing with figlet and cowsay, it prints a big dragon saying "welcome to shell!", if I see that, then I know I'm on a box I own/have sudo/am me. it's a good visual reminder. I don't fuss with prompts much, but this is a pretty good idea!