CAN THE GRAND TOURS BE RIDDEN DRUG FREE ?

There is a certain perception among the cycling fraternity (and among the public at large) that, in their present form, the Grand Tours - of  France, Italy and Spain- cannot be ridden competitively without the aid of p.e.d's. Do our readers agree with this thesis and if so, how should the format of these stage races be changed (e.g., number and length of stages, number of rest days, etc.) so that they can be ridden without the aid of artificial stimulants?