Neo,
My understanding is that graininess has to do with water retention. The "drier" a bodybuilder is, the less water he is holding. Muscle shape and separation is a different criteria. It is genetic. For example, Ronnie could be holding more water than Dorian and have more separation through his arms/delts and yet still not be as conditioned. This is because genetically, he has more distinct muscle separation in his arms delt tie-in.
I am not claiming that Dorian is destroying Ronnie in the MM comparison above. It is close, and both are very similar in condition with a slight edge to Dorian IMO. You stated that Dorian had "ho hum" conditioning which is laughable. Moreover, Dorian was 10lbs heavier in 93 than Ronnie was at the 01 ASC. Thus, he would have the edge on size and conditioning, while Ronnie edges him on separation.