You're talking Cuervo Gold. It's mixto. If it's 100% agave, I've found that the color is probably a good indication of smoothness.
Whatever it is... look for 100% Agave on the label. If it doesn't say it, it isn't. A mixto can be something like 50% something else. Something else being flavorings, colorings, and neutral spirts which will just make your head hurt in the morning.