I never have, but my gf temporarily had free basic cable when she moved into her last apartment. The previous tenant had apparently had it for free for years. My gf even had a cable modem installed (with new cable being run into the house). About 6 months after she moved in, Comcast cut it off and now that we've moved in together, we have DirecTV.
I'm not sure whether or not I can say it's acceptable, but I can rationalize my enjoyment of it as I was paying $50/mo for digital cable at my apartment (which was just down the street) that I never watched. 😉