"Cultural fit" of candidates also applies to the company
I stumbled across a post about the secret guild of silicon valley a couple of days ago. I think it's obviously simplified for the sake of humor ("fat guys who know C++"), but there is a little truth to it.
Later on in the comments, someone mentions that their organization "... would probably pass up the type of employee you're referring to because of some B.S. reason like 'poor cultural fit'". I actually happen to agree, and yet it's not what you might think.
It's totally possible to have a cultural mismatch and thus have someone be a bad hire, and yet there is absolutely nothing wrong with a candidate. After all, a match implies an equation with an equal sign, and that means both sides of that equation are subject to scrutiny.
Let's say a particular company is filled with slackers. They like their happy little ruts. This came up in a recent feedback post where someone wrote in about "Kakonomics". In short, everyone involved likes their low-quality low-impact work situation, and anyone who challenges that is disruptive.
In that situation, someone who promises to come in and shake things up is definitely a poor culture fit. The incumbents absolutely do not want to have someone on their team who will crack the whip and actually make them work. Why would they? They're getting paid to be mediocre, and hiring this person would only change that.
Cultural fit is like asking "will this gear mesh with the other gears". You can screw up gearing from either side, so a mismatch is not always the fault of the newcomer. It can go either way.
If you're that person who comes in there full of energy and a desire to make things be awesome, and you encounter a hive full of laziness, don't feel bad if they reject you. Unless you were coming in as someone fairly high up the org chart, you'd never have any chance of fixing it, anyway. Be glad you didn't get mired in it and just move on.