In Mexico they don't use Cointreau or Triple Sec, but an orange liquer called Controy. Margs are made exclusively (for non-tourists) with silver tequila.
Authentic Michalada recipe from the state of Guanajuato, Mx:
1 dark beer
Serve over ice in a salt-rimmed, chilled glass.
Some say this is like drinking a steak and love the hearty taste. Others can't appreciate the unique flavor.