Rarity sets Rainbow Dash on a date with the boy she likes. Because Rainbow thinks he's only into girly girls, Rarity gives her a makeover. Or tries to, but she discovers Rainbow doesn't wash often, so first she has to give her a bath!
Contains: Olfactophilia, soap/washing, butt scrubbing, farts, and light, non-descriptive watersports. None of these are present in the makeover chapter, nor is nudity in any of them. I'd advise against reading this story if the last two fetishes are a turn-off for you, but I don't think it's enough for a Porn tag. It's actually more meant to illustrate how "dirty" Rainbow Dash is in this story.
This story started out as an RP I did (on a different site, of course) with OtakuBrony47. So, credit to him as co-author with me. I was Rainbow and he was Rarity. This particular one was so fun and had enough of a story to it that I wanted to adapt it into a fanfic, and he said he'd like to see it. I did make a few changes but he's fine with that. I hope he enjoys this story!
I know the scenario's pretty stretchy, she's almost certainly not really like this in canon, nor do I even headcanon that she is. To the point that I gave it an Alt. Universe tag. So, don't take too seriously.