Anyone seen this before?

Is that a common spot to rust on the car..what's amazing is below it, down in the quarter in front of the rear wheel isn't bad at all.. If there are drain holes I have to find them thru the years of crap that fell in there, not to mention the over excessive bondo left behind from someone trying to build a wall behind the rust..that's pretty cheesy...ill bet it's one of the vehicle owner do yourselfers.