USA Up All Night used to play some real schlock. Also, I heard Rat Pfink a Boo Boo was played on TCM. They're really playing fast and loose with what they call a classic movie there. Off topic, but it reminds me of seeing a movie with comparatively good production values, Danger Diabolik on American Movie Classics years ago. Its not American, its not a classic, and its barely a movie.
The Horror Channel in the UK seems to play an awful lot of Star Trek, which while it does make me shudder from how badly engineered their ships are I don't think quite counts, but back on topic, I did see The Creeping Terror on TV as a kid.
I saw ASTRO ZOMBIES on WKZO's Shock Theater out of Kalamazoo in 1971! I was only 9 years old-and I already knew it was s**t!
EDIT: National Broadcast- anything by Larry Buchanan.
Creation of the humanoids.
I saw The Last Dinosaur on broadcast TV in my youth. That was some real crap.
They used to show Ed Wood movies on a TV Channel dedicated to Cinematic Art.