Rarely the green, but it does happen.Crazy that you've noticed this. I smell weed all the time in Motown now. it seems as if every 3rd car on south street is smoking a joint. Although I've never smelt it on the green from an individual, its always been in a car. I rode the road in July a lot, and was really surprised at how cars totally smelled like weed.
It's mostly the side streets like Mccullough or Maple. It travels really far and it's impossible to know where it's coming from.
And yeah, I'm surprised too how often it does come out of cars. I guess it's not unlike smoking that you don't realize the smell if you're the smoker.