Even Mapquest directions to get to the Columbus Zoo, were at one time, completely wrong.
If coming from the east, then going north on 270, when you got off the highway Mapquest told you to turn left.
The Zoo is to the right, had it not been my first time driving to the Zoo myself where I actually had to pay attention to where I was going, I would have seen that as being wrong immediatly. But 20 minutes in the wrong direction with 4 wrong turns we eventually figured out the correct way to go.
I will agree though that Garmin is the shit.