The New York Times has recently jumped on John McCain for his history of melanoma. Apparently, he's had a history of four melanomas removed. Melanoma is a dangerous form of skin cancer, and can metastasize to other organs and cause death. It is because of this that physicians recommend you to see your doctor if a mole displays one of the following signs: Assymetry, border irregularity, various colors, size greater than 6 mm, or changes in the mole.
I've always wondered why the left side of his face looked bloated and droopy. It appears that this was the area where the melanoma was removed. I once took off a big skin cancer off the side of the face in an older gentleman like him, and to close it up gave him a virtual facelift on one side. Too bad insurance didn't pay for me to lift the other side as well. At least he takes photographs good from one side! (Yes, this is a joke.)