The intent is not just shows that got bad, but shows that were "perfect" in their first season. tat's why I included True Detective. yes, S2 was a misstep, but the others have been good. But S1 is perfect -- maybe the best television ever made.I would argue that any show that maintains a "good" status for several seasons wouldn't make this list, even if its ending sucked or the later seasons don't live up to the magic of the first season. If the show is still "good" even if its not great, I don't think its a candidate.
compared to like Heroes for example that starts its nose dive right from the 2nd season.