At a high level, would you want to be working alongside that person as a teammate? If someone were to write in the interview summary, "the candidate is really bright, but arrogant as all h*ll; I wouldn't want him/her to be on my team because he/she would be incredibly painful to work with", that's a pretty strong signal to the hiring committee.
So someone who spouts off racist, or presents as a brogrammer (i.e., cracks sexist jokes or throws around terms such as "gang bang", etc.) --- definitely not Googley.
Of course, it's harder to detect the more subtle forms of "someone I wouldn't want to have as a teammate" in a 45-minute interview. So more often than not, what I end up putting in that section when I do interviews is "no issues noted". The good news is that many of the more nuanced forms of "googleyness" are hard wired into the culture, and so new hires tend to pick up on these sorts of things through osmosis and seeing how more senior engineers behave. Things like gathering data to back up theories, and not just making assertions, or writing code very defensively and with a heavy emphasis on testing, etc.
Of course, these highly desirable attributes aren't unique to Google! In an ideal world, these sorts of things would be the base level of what would be assumed by all engineers across all companies! Unfortunately, those of us who have worked on many companies know this is not true --- and there will be a few bad apples inside any company, including at Google. But on the whole, I have to say that Google's hiring process tends to do a much better job weeding out "engineers I'd rather not have on my team" better than what I've seen almost everywhere else.