I'm not sure how but one time I started getting a few ads in Spanish about toothpaste. I had also just found out about the ad settings page, and after taking the minute to remove the handful of wrong interests, the incorrectly targeted ads stopped.
Edit: Facebook allows it as well, here are the links for anyone that wants to do it now.
... improve the tracking accuracy of your data in exchange for reducing your annoyance with ads
But personally I like targeted advertising. Ads let me use services for no monetary payment while still providing income for the content creators, and I like seeing ads that are targeted towards my interests more than ads that aren't. And while it's not ideal that you might have to go in and change what your preferences are in cases where they get it wrong, I much prefer it over the alternative of all ads being "wrong" for me.