Well now, that's rather odd. I have fond memories of spending hour upon hour with my family in the 60's and 70's watching all kinds of TV in the evenings. And there were a lot of very good, entertaining programs and a few boring ones. But I don't remember any of this X-rated dialog or other filth we have now.
And here's where my memories part ways with yours - For some strange reason, I don't remember there being just the one single PBS station on the airwaves. I coulda sworn there were 5 Denver stations. But from what you say, PBS must have been the only station on, because censorship was so much heavier back then.
Maybe I just dreamed up all of my childhood?