I have Done it twice, Once when I didn't see the person as she came out behind a van and once when it was unavoidable, both times I stopped, handed them a towel and gave them a lift home.
I would never do it purposely, most times I slow down to a crawl so as not to splash them,
it's just a dick move, I would be pissed if someone did it to me so the same goes for them.