if we assume everyone is cheating it's obviously not a level playing field because you don't know how much each cyclist is doping. if everyone is cheating and landis won, it'd be a stronger statement to say landis is the best doper of the bunch, not the best cyclist.
i'm very new to cycling but i have a strong background in participating in competitive sports, and one thing my coach taught me that i will never forget is that crossing the finish line first is not what defines a winner. if you dope you don't deserve to win, period. i don't care if you get caught or not. call me naive, but if everyone in pro cycling is doping, then nobody deserves to win.