In the case of the latter, it was the studios’ belief that audiences couldn’t handle too much zany comedy in a movie and needed the romantic sub-plots (and musical numbers) as breathers. The films the Marx Brothers did for MGM are also notorious examples of this.
Hell, 1968 was “a long time ago” by 1971.
The “comic relief” ST:TOS episode “I, Mudd” was embarrassingly bad doublepluscringeworthy in its entirety.
A lot of Hollywood movies still add romance subplots even when they add nothing to the movie. Pearl Harbor is one of the more egregious examples I can think of. You mean to tell me that the bombing of Pearl Harbor and the subsequent Doolittle Raid wasn’t dramatic enough so they had to add a lame love triangle to the story? I believe many producers think this will appeal to women in the audience so that’s why we get lame romance subplots. And, holy hell, Pearl Harbor is an old movie now too!
I can’t think of any old bad comic relief in television dramas off the top of my head. But, yeah, the clown music that would play during such scenes rings a bell.
I thought they added the romantic triangle to Pearl Harbor to make it more of a classic war movie.
Action movies both made and set in the 1990’s-2000’s had ubermench special forces elites protecting a fat post-Vietnam society of family guy sclubs from evil. 1940’s movies had the schlubs themselves obligated to do the fighting.
The dwarf tossing jokes in the Lord of the Rings movies.
Yeah.
Plinky ‘pizzacato’ string plucking is a cue that humor is happening. Usually during a farcical scene where someone is sneaking around on some silly mission to get out of a jam.
Thirty Seconds Over Tokyo is unbearable to watch, IMO, because of the icky glurgey sickly sweet marriage of brave Van Johnson and his awesomely loving knocked up wife. I want to puke, it is so over-the-top as she plans to sit at home and gestate, holding back tears, while her hero is off doing his millitary duty.
I just saw the first season “Dale the Whale” episode - Monk took a visible delight in Dale’s impotent rage after Monk solved the case (also Monk was intensely irritated by the sauce dripping down his therapist’s face when they met during lunch hour - but Monk was not freaked out, just irritated).
Oh man is it ever glurge-ey AF. The domestic saccharine is horrible as you note. While flying and he finds out his wife is expecting, the sing-along of ‘rock-a-bye-baby’ by the bomber crew as they bank the plane back and forth made me near throw up in my mouth.
It’s almost Saturday Night Live over-the-top. 
Even this one?
Not sure this really belongs here, but….
I watched an episode of the Adam-12 TV series from 1969 entitled “Log 172: The Things You Do for the Job.” In this episode, Officer Pete Malloy (Martin Milner) is stalked by a rich 20-something woman (Ahna Capri, best known for Enter the Dragon) whom he ticketed for speeding. She insists on dating him despite Pete telling her repeatedly he is not interested (“You turn me off!”) Among other things, she makes several false reports to the police to lure him to her and even tries to give him a Porsche 911 Targa!
After being told by his supervisor to settle the matter, Pete finally gives in and agrees to a date (despite the fact he has already claimed cops are forbidden from fraternizing with those they encounter on the job). We never see the date, but Pete tells his partner the next day that they had dinner, caught a show and went dancing. He then adds cryptically: “She’s not gonna be a problem anymore. Not at all.” His partner smirks. The end.
While the ending may not be “embarrassingly bad comic relief,” it seems intended to be lighthearted… and yet the unmistakable finality of Pete’s assertion and his partner’s understanding smirk have decidedly sinister undertones. A detailed episode description with screenshots as well as various theories about the ending can be found on this blog…
You realize, of course, that the movie is largely biographical. Pilot Ted Lawson was a real person and participated in its filming. The however sappy they may seem, the events depicting his home life were more or less accurate.
As much as I love Columbo, I often cringe at the attempts to inject some levity into his murder investigations. Especially when violins are being plucked in the background. I think the longest such sequence occurred when he was trying to get some information from a Human Resources officer who was in love with her computer. (She now reminds of Catherine Tate’s “Travel Agent” character—“Computer says ‘No!’”)
On his way out, of course, he retrieved the cigar he was forced to put out while he waited. 
The Pakleds most certainly weren’t comic relief. In universe, that their dimwittedness provoked mirth, pity, or confusion was something they deliberately exploited in order to gain the upper hand in interactions with alien species. And by extension, out of universe, their apparently risible behaviour was not humour for humour’s sake, but rather a device that the writers used to surprise the audience with a plot twist.
oh yes, I got that… Doesn’t make it any less sappy. 
I guess we’ll never know what he did with the body.
That’s the best kind of blowed up.