* If Sam is a recovering alcoholic, how can he work in a bar without serious risk of falling off the wagon? This alcoholic Troper was 2 years sober before she could walk down the wine aisle in the grocery without getting weepy and doubts she would ever be safe working behind a bar.
** He bought the bar while he was still wealthy and a drunk. He owns the bar because a) he has no other income, and b) it's a constant reminder of just how far he's come.
** I have indeed met a bar owner/operator who was a recovering alcoholic.
** Without wishing to diminish or dismiss the OP's struggles or difficulties, different people struggle in different ways, and they find different ways of coping with their struggles. Some recovering alcoholics, like the OP, find it difficult if not impossible to be near alcohol or the temptation it provides; others find it easier. Given his occupation, Sam is presumably one of the latter.
** Also, being in the bar allows him to be surrounded by friends who would help keep him on the wagon.
*** That makes sense; Sam bought the bar shortly before going sober so he probably feels like it's easier to not drink there since he's been on the wagon since buying it. Conversely, he mentioned he can't hang out with his old drinking buddies anymore since he feels the need to get drunk whenever they're around.
** Not meaning to trivialize the struggle with alcoholism, but I imagine it'd be sort of like a person who works in a pizza parlor; you might love it in the beginning, but after awhile you hate being around the product as you smell it all the time, and you get tired of it as you equate it with work.
* What happened to Lillian Huxley, the English waitress Sam hired to replace Diane in the 3rd season episode "The Bartender's Tale"? She isn't seen or mentioned in the next three episodes, and after that Diane returns to her old job, which apparently was vacant. Where did Lillian go?
** suppose it had to do with the Unresolved Sexual Tension.
* The staff of ''Cheers'' apparently consists of only four people: two bartenders (including Sam, the owner) and two waitresses. Yet in many episodes one or two of these people just leave the bar in the middle of their shift for a long time, sometimes for the rest of the day, and the remaining staff doesn't seem to have any problems running the bar. Why did Sam hire three other people to work there in the first place, since clearly they aren't all needed? Or why not have the two waitresses and the two bartenders work in alternate shifts?
** Convenience. The bar doesn't really need more than two or three members of staff at any one time, but having more staff than he needs allows Sam the flexibility to come and go as he pleases - which could be important if he spots a hot girl he likes. He extends the same benefit to his employees.
** On the contrary, the bar opens at 10 and closes at 2 AM -- that's 16 hours a day, 6-7 days a week. Even if the bar is only fully staffed during peak hours, it's hard to imagine 4 employees being enough.
** Most of those sixteen hours and those six-seven days, however, the place isn't going to be ''that'' busy, and in any case, based on my hazy memories of watching it the place for the most part seemed like one of those quiet little places that has busy patches from time to time but otherwise mostly gets by from a relative handful of regulars. In reality, of course, it's so that they wouldn't have create redundant characters or pay more money to cast a lot of recurring actors or extras to portray characters who weren't necessary for the story just to fill up the bar-staff.
** We could also be viewing only a certain part of the week where they happen to have the same shifts/customers.
** Norm is there all the time. He knows every aspect of the bar and the business. He picks up the slack. He even has his own set of keys.
* If Diane is a genius with several degrees, why hasn't she any options but being a waitress without a lover's patronage from her uni?
** Diane does sort of seem like she'd be hard to employ as her self-centeredness cuts into people skills, and she starts off the series still in college (''working toward'' a degree doesn't do much for a resume- trust me). Also, if I recall correctly, she started the series having never worked before and it is ''really'' hard to get a job with no experience. As for after she graduated.... I'm sure she probably just wanted to keep working so she could stay close to Sam, which is why he kept employing her (though they likely had some excuses for it).
** She may also have gone back to school. At one point she says she's very close to getting a master's degree, then adds that she's close to a whole number of master's degrees. The implication at least in the first few seasons is that she keeps changing to different degrees, never completing them. So part of the problem seems to be that she can't settle on what she wants to pursue, which would continue on a personal level even after completing a degree.
** Even if it wasn't abundantly clear that Diane, while BookSmart, isn't nearly as clever as she likes people to believe she is, being a genius ≠ being employable. Diane might be clever, but she's also quite flaky, neurotic, a bit unreliable and possesses a personality that rubs many people up the wrong way (pretentious, smug, condescending, a know-it-all, etc). It's not entirely surprising why potential employers might not consider her a particular catch for their organisation.
*** Diane states that she has "numerous alma maters," but never really says she's finished any of her degrees (at least, past her undergrad). Unlike the skill-heavy and (relatively) technologically advanced programs that are prevalent today, Diane has few practical skills in addition to the already-noted grating personality. She probably also has quite an accumulated student loan debt, which keeps her working.
** It's hinted at in-universe that her family is wealthy, which would allow her to continue her studies without loans, to a point. At the time, as the previous troper pointed out, academia didn't really prepare people for the "real world." She lacks any real skills or work experience, and she's not the type to get her hands dirty. She probably meant to have an academic career, teaching university, but she also failed at that.
* Why doesn't Robin seem to show any interest in being alone with Rebecca? It comes across as a very needy, one-sided relationship, yet he is spending lots of money on her in gifts and dates. Ignoring the fact that he's a real jerk, it seems odd that Robin doesn't seem to want to sleep with his own girlfriend that he's been dating for such a long time.
** Robin is arm candy. She's too crazy to sleep with.
** He was only dating Rebecca to get her computer password to spy on the company she worked for.
** In the early going, at least, he was dating two other women at the same time he was dating Rebecca. Presumably his needs were being sated there.
* Why couldn't Diane write while being married?
** It wasn't that she ''couldn't'', per se--so much as she (supposedly) ''wouldn't''. Sumner acts as if it's impossible--but his reasoning is that Diane would be far too occupied with her relationship with Sam to do something as major as "write the Great American Novel" in her spare time. While on its face a rather absurd notion...the fact that Diane herself admitted she hasn't continued on her book since she first came to Cheers ''seems'' to give at least ''some'' credibility to Sumner's argument--at least, enough so that Sam's vision of his future with Diane has her as never having finished the book.
* Why is Carla the ''only'' waitress at the bar when the corporation owns it? When Diane leaves for Europe in Season 3, Carla is pressuring Sam to find a replacement, so she won't have to deal with the increased work load. And yet, Season 6 on, suddenly the issue is basically shrugged off and never really dealt with.
** Because Carla has a lot of kids, odds are she ''wants'' the extra work now so she can afford all her bills and food expenses. Even if she doesn't want to work, she sadly doesn't have much of a choice.
* How on Earth did John Allen Hill somehow get enough clout to "claim" the part of Cheers with the bathroom and pool room as his own? Last we heard, the Lillian Corporation owned the ''entire'' bar...and sold to Sam the ''entire'' bar. Therefore, the ''entire'' bar--pool room and restrooms included--is ''Sam's'' property. So how did Hill get part of it?
** In the first episode with Hill, he produces blueprints that show that the poolroom was originally part of the restaurant and had never changed hands. Sam might be able to fight such a claim in court, but he could very well lose.
* In "Power Play", emphasis seems to be placed on the show Diane's watching on her portable TV (just before Same comes back)--we actually hear some the dialogue. Were we supposed to get the idea she was watching a "real" show (and if so, which show was it?), or was the dialogue we hear from the TV just recorded for the episode?
* A few episodes mention Sam can't have platonic relationships with women, or ever have a women who he doesn't try to form a sexual relationship with. Why do these episodes never mention his friendship with Carla?
** I don't remember every relationship Sam ever entered into in the show, but it's possible that there's an unspoken implication that Sam can't have a platonic friendship with ''unattached'' women; if Carla was married when they met, he may have simply decided she was unavailable and so didn't bother pursuing her to begin with. So Carla might not 'count', so to speak.
** Sam does at one point say he doesn't go after married women (and is implied to dislike the idea of cheating on one's spouse). But even with that, he and Carla have had ShipTeases here and there, and even flirted with the idea occasionally, but always decided they were better as friends. It just doesn't seem like anyone mentions that when talking about how he has to get sexual with every woman he meets.
** Sam probably thinks of Carla as a sister. That's another line he won't cross- unofficial or not.
** There's also the simple existence of a little thing called 'hyperbole'. When people say Sam "can't have platonic relationships with women", this doesn't necessarily mean that they are literally saying that he is completely and totally incapable of having anything along the lines of a platonic relationship with a woman and it's an unbreakable law of the universe, they're just emphasising what a huge skirt-chaser he is.
** Also, the implication with this statement is that Sam is incapable of having a platonic relationship with a woman ''that he is attracted to''. Judging from the women we see Sam chase over the years, he clearly has something of a type, and it's also clear that Carla does not really fit into that type physically or personality-wise, so the simple answer is that Sam is presumably not particularly attracted to her. The guy's a womaniser, but that doesn't mean he lusts after literally every woman on the planet; there's going to be some women that for whatever reason just don't do it for him, and we can safely assume Carla is one of them.
* Why did the writers bother getting Frasier and Lilith back together six months after she left him? Lilith never appeared on the show after they reunited, and they would be separated again by the time the spinoff began. It would have made so much more sense to let them divorce, given that it was going to happen anyway.
** When ''Cheers'' was ending, no one initially expected that a spin-off was going to happen. When Kelsey Grammer and the producers began planning their next project, they were originally intending to do something completely different (fun fact: Grammer was going to be a housebound paraplegic millionaire) but the network pressed them for a ''Cheers'' spin-off. So when they came up with ''Frasier'' everyone involved deliberately stripped away as much from ''Cheers'' as possible to avoid simply making a ''Cheers 2.0'' and getting slaughtered with endless ''Cheers'' comparisons by critics / viewers (hence the move to Seattle, the classy cue cards, the smooth-jazzy opening themes, Frasier being a radio host and basically everything about the show except for the presence of one Dr. Frasier Crane) and his marriage to Lilith was a casualty of this, since their dynamic would have likely reflected their relationship on ''Cheers'' too closely. Since no one planned for the spin-off, the Frasier / Lilith reunion was likely supposed to be their final "happy-ever-after" ending, but it ended up being undone when the creators of ''Frasier'' decided to go in a different direction. If anyone needs an in-universe explanation, it's simply that -- like many real-life couples -- Frasier and Lilith attempted a reconciliation, realised it wouldn't work, and just divorced for good.