Friends can enter each other’s apartments at will: doors are never locked and visitors never bother to knock.
A character who never drinks will instantly turn into a raving, babbling jackass after one drink.
A scene that opens with a tight shot of a character in bed will pan back to reveal that character in bed with someone (or something) else.
(In other words, last night’s Big Bang Theory)
That first one isn’t Big Bang Theory, they knock all the time on that show (boyfriends and girlfriends are the only ones who seem to have open door access).
This one, like sitting three to a table, is somewhat needed for the camera. Pulling the couch away from the wall lets some of your characters walk behind it that way they can interact with the people sitting on it without standing in front of them (and between them and the camera). Of course, having a couch not against the wall means having a bigger room to accommodate that.
Rosanne managed to still have a smallish (looking) living room/house, but even that was bigger than my house and I probably make more than those two put together and I’m in considerably less debt. It’s just one of those TV things, you need the space for the people and the cameras to move around and make it all look nice.
The size of their house never bothered me. The biggest houses we lived in growing up were when we were poorest.
Amusingly, as I’ve gotten richer the size of my residence has shrunk (because I’ve been in more expensive urban environments instead of poorer suburban/exurban environments).
While I understand why most of these things are done (watching someone go open a door is just a waste of time so have the person just walk in; in a three camera set up having a restaurant booth against a wall creates camera problems) the two I like are:
**You can’t stay mad **- No matter how fucked up of a thing that another character does to you…YOU CAN’T STAY MAD.
Your spouse must not like their in-laws - They can be tolerant of them, but they must never like them.
Owing people money must always be played for laughs - Despite debts being long-term sore points in real life, if you owe someone money in a sitcom its always funny.
Your boss is either a goofball or a hardass - Thou shalt not have an intelligent and understanding employer or supervisor.
You have ample time to goof off at work - Apparently no one in sitcoms ever works at an understaffed, high pressure job as they constantly have time to goof off, go to lunch and riff off of a hilarious co-worker. Deadlines don’t exist in sitcoms.
If you have a disagreement with someone you share a house, apartment, or business with then the solutions is to draw a line down the middle of every room and each person stays in their half.
If the lead family has a baby, by the next season (if the show lasts that long), the baby will be in grade school, even though no one else in the family will have aged. There will be no explanation offered for this.
Either that, or the show will be gone by the end of the current season.
Characters talking to others on the phone will always repeat whatever the person on the other end said. (“What’s that, Bob? Mom’s in the hospital and the dog’s run away?”)
Any servant or underling whose mother is about to visit will reveal that she believes it is his house or business, and everybody will act in that way when she is there.
They do sometimes, when necessary to create hilarious hijinks.
Important things going on in your life must always be hidden from your parents (for hilarious hijinks). That is, until they find out and even more hilarious hijinks ensue.
If your show has been on for several seasons and suddenly Ted McGinley is added to the cast, watch out.
Same goes for a new baby.
Whenever there’s a thread like this, I wonder whether people have actually watched TV shows made in the past decade, or whether I’m just not watching the dumb sitcoms.
Because the sitcoms I’ve watched lately (The Office, 30 Rock, Arrested Development, Parks and Rec, Community) spend a lot more time lampshading and mocking this kind of cliche than they do indulging in them (Lesley Knope’s nausea on last night’s Parks and Rec notwithstanding).
If a major character gets a great job offer that will take him or her to a different city, they will find reason to turn it down before the show is over. (Not only for sitcoms - see the Riker rule.)
In the old days children were neither seen nor heard unless important to the plot - see Richie in the Dick van Dyke show. Today I think their agents negotiate them minimum number of appearances so they are around more often.
Mocking it doesn’t change the fact that these are sitcom tropes, they’re just doing the same thing we are now. And Parks&Rec is just another example that these silly plots will endure.
If there any continuity errors, someone on an Internet Forum will flame them for breaking continuity.
I mean, whatever, obviously it’s just a silly discussion of cliches for fun… but I feel like I’ve read “hey, whenever someone goes grocery shopping in a sitcom they always get a baguette” FAR more times than the number of times I’ve actually seen someone go grocery shopping on a sitcom and get a baguette. And, for whatever reason, it really kind of irks me when someone makes these claims overbroad, as in “when you see someone get in an elevator, you’re CERTAIN that they’re going to get stuck in it”. Really? CERTAIN?
I feel like discussions of this sort are really about pop culture from 20 years ago, and no one acknowledges that. You know what doesn’t happen very often any more in movies or TV? Cars crashing into something and then exploding for no reason. And Very Special Episodes where everyone learns about the danger of drug addiction. And awkward girls with glasses and frizzy hair who get a makeover and are suddenly super-gorgeous. But these cliches are perpetuated now solely as cliches-that-people-talk-about.
What you say is valid. This conversation has gone on for decades now, but it’s still fun. However it is humor and the overly broad language is just part of the joke.
Some things like flaming car crashes have turned completely over, it’s just humor if it happens. Other tropes will continue. I expect to see wise-ass kids, doofus dads, unlocked doors and unrealistic phone calls in future shows. I watch reruns of old shows, especially very old shows because I haven’t seen them since I was a child and seeing these silly things makes them more enjoyable for me.
Has there ever been a situation on a sitcom where the cast members are enjoying a somewhat amusing and enjoyable discussion and someone walks in and tells them it’s dumb and been overdone to death? Essentially stomping the fun out of it because it may not be as fun for them.
You mean like Art Frahm?
Ha! I was going to say that, but I thought it was too obscure. I should have known better. 
You mean like the time on The Big Bang Theory where, after watching Raiders of the Lost Ark with the guys, Amy mentions that Indiana Jones’ actions during the story had no effect on the outcome and the guys are completely demolished?