We have observed a planet. Even if you were to strip it of all life, all water, all those things that make it 'special,' and then take a trip over it, you would see changes. You would see a multitude of colors, a multitude of layouts. This is a fact. This is what any sane person would expect to see.
JRowe, I realize this is probably a silly question, but when you say "observe a planet", are you referring to naked eye observation, telescope observation, space probe/orbiter observation or surface lander observation? I ask because the space probe/orbiter observations do indeed show a great deal of colors and variation in each of the planets (and a number of the larger moons) that have been observed.