Econometrics is applied statistics. When you have learned the econometrics' theory, you are free to apply it to economic data, or financial data... You can also (and people do) use it for biology, physics, etc. (even though people would call it biometrics or whatever).
The economics I have used in my econometrics courses are among the lines of "the more education you get, the higher your salary" or "if you're male you're more likely to have a high salary than if you are female".
Of course econometrics is pointless without its applications. It's a science designed to create relations in data. And econometrics is also designed for applications in economic data (if you're interested in biology, learn biometrics, but the content - at least the basics - will be exactly the same).
In fact, econometrics is divided between non-structural (or reduced form) econometrics and structural econometrics. Chances are you will learn reduced-form econometrics, that is for example examine the link between wages and education. You don't need theory for this. On the contrary, structural econometrics aims at validating or rejecting specifications from the economic theory. Structural econometrics is only useful if you're interested in macro/microeconomic theory.
Anyway, if you take courses in econometrics, it must be because you're interested in either economics or a field closely related to economics (finance for example). But for the basics you won't need economic theory. Now if you want to graduate with a master in econometrics, that's something else.
So I admit I spoke too fast, you will indeed need "common economic sense". But in my opinion, knowledge in economic theory is not required.
