Language and culture influence each other strongly. For example, formal English society tends to be rather formal and evasive. Thus, there is a rather common tendency to understate matters when speaking. Some of the common techniques involve not, un, in, double negatives, a bit and its modern cousin, challenged.
Being direct would create an uncomfortable amount of tension. So, one solution is using the opposite word preceded by the word not. It is clear that the phase it is not a good time means you should get out of here. Likewise, if something is not a good idea, it is rather stupid in fact. For that matter, if someone not looking her/her best looks awful really. You are simply not allowed, that is to say forbidden, to say exactly what you want.
We cannot forget that confusing preposition in when it means not and not in. (Now that is an unclear sentence.) An inconsiderate remarking is rude while an inopportune time stinks. For that matter, inappropriate behavior means that you are acting like an ass while if someone says you are just impossible, it does not mean that you cannot exist but instead he doesn't know what to do with you.
Un can be just as indirect. An action that is unthinkable, truly horrid, is quite feasible in thought but completely unsocial and unacceptable, i.e., rude. For that matter, crude unsavory thoughts about an attractive female in the office would be, alas, unbecoming, actually quite wrong, meaning you can get fired for sexual harassment, to say the least, if she is unwilling, or if that refuses, to cooperate. In this matter, unassuming has nothing to do with your assessment of the situation and all to do with your uniqueness, meaning completely ordinary.
Of course, a person can double down the negative, creating complete downsizing. If the gift is not inexpensive, it cost a pretty penny. People are quite aware of a problem that is not unknown. A woman who is not bad looking is pretty.
For understatement, sometimes a bit means a lot, so to speak. If the weather is a bit chilly, most adults are wearing a warm sweater. If the date is a bit overweight, she's better have a good personality. If you receive a text message from a friend saying that s/he will be a bit late, you have plenty of time to check Face book. People with limited budgets should stay away from restaurants that are a bit expensive.
Finally, in our increasingly politically correct words, people don't have problems. They are challenged. Dumb people are intellectually challenged while short people are vertically challenged. A klutz is physically-challenged. I myself am highly follicly challenged, almost bald you might say.
If all this sounds a bit Orwellian, from 1984, I would agree. We all need to be more aware of our language and say what we mean more often. In other words, be naughty, not notty!