Earlier quoted context omitted.
What happens when the Feds are knocking on your door because someone routed kiddie pr0n or drug deals through your connection?
To play devil's advocate: isn't this kind of a good thing for privacy though? If everyone routed everyone else's stuff, it will decouple the notion that IP = person. Although the service seems shady, if everyone did this wouldn't it be for the better? (albeit at cost of slower connections)
Decoupling IP from people won't happen anytime soon. It's better for law enforcement to just go, seize everything, and deal with the false positives later.
See the long list of "suggestions" for people interested in running their own tor exit node [1]. This is not something you should even think about doing from your personal home, mixed with your own traffic. It's asking for trouble.
[1] https://blog.torproject.org/blog/tips-running-exit-node-mini...