Interesting thread. If you think it looks bad on DVD, you should have seen the BBC transmissions in the nineties. The first two seasons were especially bad, with a terribly botched standards conversion resulting in some of the murkiest pictures and dullest sound I've seen. It was barely broadcast quality at times.
The DVDs are a marked improvement, but it's still pretty obvious that a full remaster from the original elements would result in a far superior picture quality. I'd love it to happen.