Looking at the ingredients, the key is freshly squeezed lime juice:

1 750-milliliter bottle silver tequila (in this margarita, the better the tequila, the better the drink)
1 to 2 cups (1/3 to 2/3 of a 750-milliliter bottle) triple sec or Cointreau
1 cup freshly squeezed lime juice, plus several tablespoons extra for rimming the glasses
Several tablespoons coarse kosher-type salt, for rimming the glasses
About a gallon of ice cubes

And yes, life is too short for bad tequila.

Try Herradura, El Tesoro, El Viejito, Patron or practically any one of the 100% agave tequilas that are available in the market.