In terms of non-exit Tor relays, it doesn't. In fact, for anyone looking at your traffic, Tor relaying is opaque, unlike legal torrents.

As for exits, you'll be dealing with abuse reports from countless parties, including the off-chance that someone sends a death threat through your exit and you have may to fend off law-enforcement that still hasn't gotten the memo on Tor. In countries, like the US where any police encounter might turn deadly, I'd highly advise against running exits at home.

As a Tor exit operator, I can in fact honestly tell you not to run exits on production business networks, or basically anywhere where you're not prepared to be a recipient of a lot of unwanted attention.