There are a lot of ideals about the way people should behave. How should they behave in their families, in their jobs, in society in general, and most of them are unrealistic, and if someone were to behave that way, said person would be immediately labeled either as a freak or as persona non grata. Weird or not, accepted or not, truth is this is the way things seem to happen. Naturally, there are a lot of "nice words", and "politically correct words" to refer to the things that are actually expected from you in order to function properly in all these circles you move in, but that doesn't mask their real nature.
One of these things is the matter about honesty and whether we are actually expected to be honest. Truth is we are wished to be honest only when honesty would be really useful, and when the truth of things is pleasant, can be handled or lives depend on it - though not even then. In informal circles - like friends and family - you can allow yourself honesty, and in this case this honestly is called "openness". You can allow yourself to tell your sibling or your friend that they look like shit this morning, or you can tell your friend and family to fuck off and mind their own business. This, however, only if your relationship with them is one of "openness", when everybody can handle honesty from themselves and others properly. In other circles that's not an option.
Perhaps you have paged through magazines or happened upon an article online about "what to say and what not to say in [insert case or situation]". Many of these go around for these circles where you can't be open - in other words, where you can't be honest. And the funny thing is that you are actually supposed to be honest... only not. Like when you go to a job interview, or when you are in the office. You are supposed to be honest and work with honesty, BUT you can't actually be honest. You can't say in the job interview that you left your previous job because, lets say, your former boss was a motherfucker who thought you are not allowed a life of your own. You can't tell your boss at the office that you won't work with their protegé because said person is lazy, incompetent and does nothing but steal other people's job. Neither can you say to your boss or their superior, when that's the case, that they know nothing and would do better actually focusing on the job rather than bother everybody about stupidities such as font types, skirt lengths, shoe colors and hairdos.
Some of the most typical cases are when you are requested to do something that's not your share. And I'm not talking about work only. There's the case when your boss wants you to do the job of the secretary, when you are not the secretary, or the job of the messenger when you are not the messenger - or worse! - the job of the engineer when you are not an engineer; but sadly there's also the case when you are at some social event, say the party of a friend, or the friend of a friend, and you - the guest - are asked to go entertain the kids, or wash the dishes... and it's not that kind of a open, friendly party. Or the case when you are in a public place and a perfect stranger imposes on you, asking you to change your seat so that their family can all seat together, or witout asking you imposes their unruly pets and/or children and expect you to put up with it.
In these cases you are not supposed to be honest and tell people that that's not your job or to fuck off and plan better with what they have, or to either shut up or shoot down their kids/pets, or go on public places when they are able not to bother others. No, you are supposed to lie. Yes, you are supposed to be a hypocrite and pretend you are not thinking and you are not feeling the way you do. You are supposed to be subservient, solicitous and do as you are imposed to do, regardless of your capabilities or disponibility for it. Simple minded people would say that you can always resign or not attend again a party, or avoid those people, BUT as things are, you can't always resource to that. You may need your job - we all do - so often resigning is not an option. You may not be able to avoid the random people who impose on you, or you may not be able to avoid the get togethers where the obnoxious people meet. If you do - as simple minded people suggest - you'll become antisocial or even persona non grata, if the person you are avoiding realizes and gets offended due to it.
Naturally we are not told to be hypocritical - oh no, being hypocritical is bad! You shouldn't do that! - but we are told to be diplomatic. But what's being diplomatic? It's being careful about what you say - which is not being honest, for being honest means that you tell the truth, whatever that truth is, in the way that represent it the best, unmasked, unadulterated. Being diplomatic is about holding your tongue about things that won't please all parties. It's about saying "let's work this together" instead of "you are so incompetent you should be removed from here and replaced with a stapler or an electric pencil sharpener". No, you don't want to offend someone by telling them they are bad, though you also don't let them know how bad are they perceived and thus helping them realize their weaknesses and work on mending them.
Naturally you could argue that hypocrisy is also about telling one thing to someone and something else to someone else. Well, think of this case - diplomatically: you have two parties, both of them unable to work together, both of them difficult and both of them wrong. If you were honest you would say to both of them together "both of you are wrong, stubborn and stupid. This won't work unless you two buttheads open up and start being willing to do this as it should. Otherwise, let's just kiss the whole thing good-bye and go killing each other". Not an option when you are diplomatic. The diplomatic solution is tell both of them, separately that you understand them, of course they are right, the other party is wrong, but why don't we seek a way to make it better, and pull the most profit out of it?. Deceivious words, often within a range of truth, but not the whole truth, and certainly designed to make each party believe that they are the ones who are going to pull the biggest benefit, or escape the largest loss.
You can call your hypocrisy diplomacy, and you know that socially this hypocrisy is seen as such only when you cross the wrong people or you get caught in it. Also, truth is that hypocrisy is often the only way you have to get to do what you honestly wish to do. You are hypocritical when you smile at the stupid coworker, and by doing so, you ensure you work unbothered. You laugh at their stupid jokes, attend to their parties, praise their unbearable kids/pets/partner/relatives/hobbies/whatever and gain their favour - all through hypocritical behavior - and thus you get them to cooperate when you need something done.
You say "well, she's a very smart woman", when what you really think is "she's a bitch that should be deported into the middle of the ocean". You say "he's really hard working" when you really think "he's a manic who doesn't know what's he doing but makes sure to annoy everybody until they can't do what they should". You say "they are very creative" when you really think "they are lazy and would come up with any excuse to avoid their tasks". Diplomatic? Sure. Hypocritical? You can bet your ass. Necessary? Sadly, yes.
This is the real world we live in, and it's out there not only in the office.