More.important to remember is that these guides are largely about promoting the parent companies. Both Michelin and San Pellegrino could pick restaurants more or less at random, generate publicity and sit back on their padded chairs satisfied that their name is in every newspaper and discussion forum on the planet.
I reckon they should choose a restaurant that doesn't exist and see if anyone notices. I bet you all I possess (not a lot admittedy) that there will be clowns in their hundreds claiming to have eaten there and found it wanting / excellent / disappointing / wonderful etc.
And Mr. Michelin and San the Man Pellegrino will still be sitting in their padded chairs grinning.