I don't know about the US but the TV licensing enforcement officers in the UK are going to have to completely rethink their approach which currently consists of driving up to homes not listed on the license database and peeking through the windows. Plus the evolution of TV circuitry and more efficient design has hampered the effectiveness of 'TV detector vans'.
Should anyone with a TV capable phone buy a TV licence?
It varies with hardware sensitivity (get what you pay for) but as a rule of thumb, anything lower than -105dBm (1 bar) is very weak and you will experience degraded service. -85dBm is pretty good. A very strong signal would be -70dBm or higher.
Alex