Re-watching Buffy the Vampire Slayer with my kids in new hi-def, and you can clearly and easily see the stunt doubles now, and the SFX look really dated now that you can see them clearly.
It's amazing what old CRTs would let you get away with.
The SFX was the limitations of tools they had, (and budget) but there were a lot of aspects of set design and stunt doubles where they could get away with more on a TV show in SD compared to a movie that was on film. When HDTV started, even news shows were forced to drastically improve the quality of the set pieces and makeup because small details could now be seen.