I'd assume that nearly everyone in a grand tour is doing grey area stuff, with a slight majority doping blatantly. I doubt that they're doing blood transfusions anymore, but they're probably on highly specified regimes throughout training camps. Further, I think most would still sort of believe that they themselves are clean. People have a great capacity to convince themselves. Of course, if someone rises to the top of a doped out field, odds are they're doping as well.
As a viewer, I think it's a lot more interesting to watch these events as great arms races, with athletes using training methods, nutrition, and doping to gain marginal advantages over the field. Viewing this stuff as a part of the sport greatly increases my interest, and decreases my disappointment when it turns out the world champion beating doped records did in fact cheat.
I think being disappointed about doping reflects a perception of these sports as an amateur activity. We want to believe that at the top level athletes are still fundamentally the same as competitors in a high school dual meet. But it's not, there's millions on the line, and these guys dedicate their whole lives to the sport. Don't think of it like Tadej is an amateur, think of him as a dedicated pro doing everything in his power to win. It's a lot more fun this way.