I have analog cable, not digital. The cable company also sells phone and internet service via the same cable. I suspect these and other signals are interfering with the local channel signals, causing interference patterns, etc. The signals are watchable, but have interference.
With DTV, if it is working, there is no interference.
As to the killing of broadcast TV: see this website:
http://broadcastengineering.com/news...217/index.html
The phone companies are trying to take more spectrum away from Broadcast TV. It will only get worse unless people protest.
I agree with you about the huge mistake. In fact, from what I have read about using VHF channels 2-6 for DTV or mobile apps, these should be re-allocated back to analog TV. I know of two stations that were allowed to move from these bands to UHF bands as the DTV reception was so bad. I have also read that the antennas for mobile apps are to large in this area of the spectrum.
The other mistake the FCC made was selling the spectrum. It would be better for the US taxpayer if they rented the spectrum for certain periods of time(just like the phone companies do to their customers).