They are pretty common. It's just people celebrating that which they grew up liking/loving.
If done to a 2013 Mercedes, now in 2012, I'd question it, but I love the expression and art of it on the vehicles they choose to do them on.
I've seen some neat ones here in south Florida, but for the life of me... can't remember what they were.
Too, they very well may stand out on purpose, and be easy to memorize, as drug sales points (drug dealers), but meh, I'm not against non-family members using drugs anyway. I don't know if that's how they're all used though - but I think you've got to agree that that type of painted 'art' is much more pleasing to the eye than graffiti - which was the old style of 'art' such cultures used to use.