Ask HN: How to find good company culture fit when looking for jobs?

I'm not part of the main job market (programmers looking for work at interesting high-tech companies) that most Hacker News participants are in, but my children, and my friends' children are. In conversation with a parent of a hacker, the question came up of how a young hacker would know which company is a good cultural fit. One cultural fit issue is big, established company versus small startup, and another cultural fit issue is software shop versus technical department in a non-software business. That kind of information is disclosed by company websites and news stories. But what about drinking at all company parties versus not having much company culture of drinking alchohol? How apparent is it to job-seekers how many hours an employee has to put in during "crunch time," and how apparent is it how often crunch time happens? Which companies are most friendly to extraverted people, and which are most comfortable for introverted people? And so on. How does a young job seeker find out what aspects of a company's culture are not mentioned in job announcements that still matter for fitting in at the company?