Turns out, TV viewers will forgive and forget

The Michael Scott-less final seasons of "The Office" demoted the series from light classic to shopworn comedy.Chris Haston/NBC

How often do good shows get run into the ground by network greedheads milking their hits for more money, more viewers, more attention? Very often, alas.

There’s a too-long list of the belabored, and it includes “The Office,” “Homeland,” “Scrubs,” “Modern Family,” “Friends,” “Dexter,” “Weeds,” “Twin Peaks,” and, famously, “Happy Days,” the show that gave us the oft-used metaphor for overstaying a welcome, “jumping the shark.”

It’s sad watching a once-fine series peter out slowly, serving up a silly romance (Joey and Rachel) or an incestuous relationship (Dexter and Debra) because all of the more organic plot twists and tropes have already been used at least twice. And it’s maddening, like watching a valued friend make one bad decision after another. Every time an outstanding series runs dry, an angel rolls his eyes.

The awful later seasons of a series also leave permanent blemishes on that show’s legacy — or do they? Years and years after a series ends, do we remember its slow decline and ultimately think less of it? Is its inferior final third or fourth a fatal flaw, one dooming it to the lesser eternity of also-rans?

I’ve always felt that those two mediocre seasons of “Arrested Development” have tainted the way the show will be perceived forever after, and that the post-Michael Scott seasons of “The Office” demoted the series’ classification from light classic to shopworn comedy. Without that last, redundant final season, and maybe two of the seasons that came before it, “How I Met Your Mother” might have been an all-timer, a rom-com ensemble sitcom that would have landed on many of the Top-Best lists. Same for “Modern Family,” which lost its bearings after season five or six, but kept on going nonetheless until season 11.

“Scrubs” was also an all-time top series for about five seasons. With a tone that reached from slapstick to moving drama, it had strong “M*A*S*H” vibes, and the surrealistic flashes were inserted brilliantly. And then four more seasons came along, and then for the ninth season there was a new cast with some of the elders mixed in, and then it all looked more like the worst freshman dorm party ever than a paragon of TV comedy. Speaking of “M*A*S*H,” it too lost its mojo along the way to its 11th-season finale, particularly as the characters became more “likable” and Radar left.

A scene from "Scrubs." The series was in peak form for about five seasons before it hung on too long and went into decline.Mitchell Haaseth/NBC

But my long-held thoughts about a show’s legacy, and the likelihood of permanent damage, may well be misguided . . . OK, wrong. I’ve just assumed that, when looking back at a show, viewers would probably give the last seasons as much if not more weight than the earlier ones. After all, the later seasons are the most recent ones and, perhaps, most vivid in our memories.

Recently, though, the Globe hosted a competition to find out which show readers feel is the best of the last 50 years. I learned a lot from it, as I got to see what non-professional critics think and feel. The winner was “All in the Family,” and along the way to that happy and unexpected conclusion, a number of over-extended series scored quite well. It seemed as if few voters were concerned or critically turned off by the sense that their favorite shows had lasted too long (or, perhaps, they felt the shows had not degenerated).

Dragged out titles such as “Friends” — which fell into late-stage desperation — hung on much longer than I expected in our bracket. It’s heresy, perhaps, but I think even “The Mary Tyler Moore Show” lost its way in the last two seasons, after Rhoda and Phyllis were gone, Ted and Georgette were primary, and Mary was in a new apartment; nonetheless, it was in the game until the final four, when it lost to “Seinfeld.”

So all my kvetching about legacy over the years may have been overstated. I’ve always known that a mediocre series finale, while annoying, would not leave a permanent mark on a show’s record. Series finales are impossible assignments for TV writers who are paid to keep a story going for years, and for every good one (“The Americans”) there are 10 forgettable ones (“Will & Grace,” “Seinfeld,” “Game of Thrones,” “True Blood,” “Gossip Girl,” “St. Elsewhere” — OK, I’ll stop now). But it turns out those final seasons of once-great shows, so weak and unnecessary, also fail to scar.

I suppose memories blur the specifics across the years, and many of us simply remember the best of a series. We remember what it did well, how it may have broken new ground when it appeared, and the strong writing or ensemble interaction. Perhaps we even romanticize, as a show has wended its way into our personal history, a part of ourselves. No one has to be remembered for their worst moments.