Okay, I think some people are referring to "digital" cable and it's not really digital. Maybe the cable co is telling them it is, but it's not.
"Digital" cable should not be receivable on a standard TV without a digital tuner.
I have a few channels in my lineup here that are broadcast in analog and "digital" 480i. There is a noticable improvement on the 480i version of the broadcast, better color seperation and fewer artifacts. This is on Time Warner basic cable, in Western Ohio, without a cable box. My TV has a QAM capable tuner onboard, so I'm able to get like 15 unencrypted channels (CBS, FOX, and like 12 PBS channels).
Your "digital" cable box may be just repeating analog channels. A true digital channel should have a funny number if you're viewing it on a regular tuner, all bets are off through a cable box. Here, my digital channels are 7.1, 7.2, 14.1-14.6, 16.1-16.6, 45.1, 48.1, and 48.2. That's all through cable, I don't have an antenna connected for OTA.