to become a 3*, the restaurant must meet certain physical requirements not related to food. cloth napkins of a min. dimension. chrystal water glasses, plate plates of a certain dimension and about 100 other nit pick thing.
in the '80's my wife and i ate in about 15 of the 20 3*'s outside paris.(the others were closed for the winters). we found all to be superb. during the same period, we ate in a large number of 0,1, and 2*'s. the main differences to the 3*'s(and the hopeful 2*'s) we saw was the ambiance and the lack of the ultra exotic concoctions(not necessarily a determent).
about 5 years ago, we ate in two 2*'s in paris. in both, we got unbelievably wretched service, and we thought the food was lousy.
also, about 5-10 years ago in Nice, we made a point of eating in The CHANTECLER in the hotel negresco. they had lost all 3 *'s, and had gone from 18 or 19 (of 20) points in gault million to no mention.
interesting experiment. the ambiance was beyond comprehension. very very formal. the food superb. somebody just said "go away food raters"
as an aside to that meal. we sat next to an extremely large round table that had been roped off(red velvet). a grand dame was dining in a very large special chair. the other two chairs at the table had pillows on them, and two small white poodles.