If I'm using a pre-made mix for whatever reason (and it does happen some times, let's face it, sometimes I'm lazy), I'm not too concerned about using a decent tequila, and will use just about anything on hand. But if I take the time to go through juicing things and make my own mix, I'll definitely use a decent tequila, I can taste the difference in the end result, and for me it's worth it. (For that matter, I'm never going to drink tequila straight, regardless of the quality, I just don't like it straight.)

Now, that said, all the crappy tequila is finally out of my house, and all I have left is decent stuff, so I generally go through the effort of making the mix myself. Neither my wife or I is a heavy drinker, so I can pretty easily whip up enough to get us through a weekend.