What a fun thread!
Overrated:
Café Tango: I used to like it, but it seemed to slip some last few times to the point of being mediocre for price.
Mi Cocina: Just not that great and unless you are out on east end of 30-A, far cheaper and just as good (to better) options exist close by.
Gems:
Café 30A. Abrazzo. Trebeache (now that George is there, it used to be iffy). Steamboat for grease. Bruno's. Sushi at Old Florida Fish House (I gave up on main dining room years ago). Breakfast at Great Southern. McTighe's for late night grease. Red Bar has very good food but is not worth the hassle in busy season.