Spam and Spyware are already under intense legal pressure, so your idea, although somewhat valid, wouldn't really hold up compared to the far more serious compplaints.
Spam and spyware couldn't account for that much bandwidth anyway, so unless you have a pitiful low cap, I doubt it would ever factor in.
Depends on your connection. If you have a metered line ( you pay x for y units of bandwidth ) you might have something. Good chance that if you can't quantify it in dollar amounts, then you really don't have a case.
Now, granted, legal fees alone would be monstrous here. But in theory, it could work. Further, for the case to have even more merit, you'd want to make sure they stole enough from you ( remember, we're talking cost$ now ) to be more than a misdemeanor ( which, I believe it's a misdemeanor<sp> at something like 2 bucks + ). And on top of all this, it'd need to be a single company responsible for it all.
So IF you have a metered line, and IF it's ONE company that cost you more than X amount ( cost of felony charges? *shrug* ), then you MIGHT have a case. Only then can you pay some sleaze ball lawyer obscene amounts of cash to win back the X amount ( which is probably trivial to the company ).