Unfortunately, producers can label a spirit “tequila” even if it isn’t 100% agave. Cuervo is the first one that comes to mind. Most of their line is classified as “mixto” which means they mix their product with grain alcohol (if I remember correctly.) This basically gives them more product for less 100% agave spirit they make/purchase. Of course, Cuervo also has their Tradicional, which Sean mentioned above, which is a 100% blue agave tequila.

Camper has a very interesting article that touches on this here: http://www.alcademics.com/2009/02/the-trouble-with-tequila.html

I’ve read a few articles that argue Mexico should regulate tequila and mandate that in order to be called “tequila” it has to be 100% blue agave. Personally, I can’t say I disagree with this argument. There is a distiller on the Left Coast (and for the life of me I can’t remember who it is at the moment) that is making a 100% blue agave spirit. But they can’t call it tequila because it isn’t made in Mexico. I would argue that it is more of what a tequila should be as opposed to the mixto tequilas that are on the market. But what do I know?!?!?

Cheers!

Isn’t it legally not tequila unless it’s 100% agave?