The first controversial tree that always comes to mind for me is on the par 3 8th at Bethpage Black. With a relatively flat putting surface, the tree forces significant thought from an elevated tee and makes the hole much more difficult. Limbs overhang the right side of the green and make it very hard for any shot other than a fade to get anywhere close to the right half of the surface. Does it make it better? Not sure. But it does make the hole harder and less straightforward.