Chef's and maitre d's have commited suicide after losing a star; but not recently (Michelin ratings aren't as business significant as they used to be, now Food network stars are equally important monetarily). Michelin has a meticulous methodology and while there have been whiffs of scandal, Michelin has proven the integrity of its process over decades.

The catch is that the rating criteria may not match your own dininig preferences. For example the difference between 2 and 3 star might hinge on what kind of fountain pen is provided for you to sign the bill (an exaggeration, but it is an actual rating criterion and one of many non-food quality aspects in the stars). Overall the Michelin red guides have proven to be the best by far (zagat and egullet not withstanding), imho. They do include non-star rated restaurants that are worth visiting (to Michelin's credit).