Are you saying that all television sequels suck or that everything that sucks gets a sequel?
Well, depends on the series and other stuff.
If it was a series from the 70/80/90 it's obviously going to suck if the sequel is made afterward in like 2005+
The same goes for games.
Not always but most of the times.
Best example here would be Sonic The Hedgehog. Everything past 2000 sucked richard and still sucks richard.