The 11th green at Granville Golf Club, an old Ross course in Ohio where I went to school, has sunk some three feet since the course was built in the mid-20's. The front of the green has literally just fallen down, which doesn't really affect the approach to the green (visually), but a middle left pin position is one of the most difficult places you'll ever see a pin. Borderline unfair, if that's possible. First time visitors to the course usually walking away thinking that the green contours have something to do with the bold genius of Donald Ross, but the old-timers will tell you that the original green, though contoured, was much more level and that the green has evolved into something it was never meant to be. Maybe it was a construction mistake. Maybe they just used some bad fill for that particular green. But, yes, it's pretty common.