A relatively common annoyance I find is this: A person will make a list of requirements for something, and one of those requirements is both crucial and very difficult to obtain. Let’s call this characteristic “X”. Besides the X requirement, the other requirements are either (1) relatively easy to get and/or (2) not as important. The problem is that the list-maker will act like the “X” requirement is just another item on the list, when in fact, the “X” requirement should be written first on the list, bolded, and written in all caps. The "X" requirement is the first thing people should read -- it utterly disqualifies the most potential matches.
Here’s an example: I recall reading in a local paper the 5 requirements of owning and operating a yacht: (1)a willingness to learn new things, (2) good seamanship, (3), a love of the outdoors, (4),substantial disposable income and (5) sobriety. Clearly #4 isn't on-par with the other items. The “X” requirement is not only non-negotiable , but also very difficult for an ordinary person to overcome.
The world of dating is replete with this. Just recently a female acquaintance of mine who dates only very good-looking men making over 150k a year posted a dating ad where she lists these requirements, but the header says “Must love my cat and be drug-free”. I wanted to tell her that in a more practical dating world, people would list their “X” requirement in the header. But is there a proper word for “X”?