It is amazing, Skittles has outsmarted me on numerous occasions. Its the determination that drives them. Its the tricks that they teach themselves that are not only amazing, but most the most rewarding (even if it is 'mischievous').
The good thing is, it can also work in your favor. If you act just as determined and remain persistent, then behavioral training can be rewarding as well and just as successful. While I didn't teach him, Skittles is potty trained. He was trained by the pet store clerk at the local pet store I got him at. Its made having him free-flighted so much easier. He and I also have an amazing communication system. He knows just what to do when certain things need addressing which really keeps his screeching to a minimum.
Here are just a few things he does: When he wants a bath, he will fly onto the kitchen faucet. He'll ruffle his feathers and sneeze. That means he wants a bath. Not only that, but he does his 'three bears' routine. I try my best to get the water temp just right, but he'll put his foot in and if its too warm he will take it back out and just look at me. If its too cold, he'll ruffle his feathers. When its just right, he goes right in. If he wants juice he flies onto the top of the fridge and screeches (not screams). If his food dish is empty, he'll grab it with his beak and smack it up and down. Or, he'll fly over to his food bag or treat bag and screech (not scream). I even color trained him to not chew on my 'non-white' shirts. The thing with that is, he outsmarted me on the color training too. You see, he can tell which food bag is which. Even though they are the same exact style bag, one has a red label in front, the other a purple. He knows which is which, and even if I try to be sneaky, he'll figure it out. The pellets are the same size too.