The doping shouldn't really bother me, since it's been going on forever, including years when I paid great attention to the TdF, but the Puerto-related stuff just seems too sleazy for my taste. And I suppose we shouldn't have too many illusions about any professional sport being drug-free...
I'm following the Tour casually, enjoying the spectacle but not caring overly much about the results. The field seems wide open this year, which is a plus.
I followed the Giro much more avidly this year, as I find it (esp. the Dolomites) much more beautiful than the TdF, and some of the mega-climbs (Tre Cime, Zoncolan) were spectacular. I don't expect this Tour to match the Giro for excitement. [Yes, I know that the Giro's probably more "dirty" than the Tour...]