This was a great read and I've seen this kind of thing first-hand at a few companies I've worked/interviewed at.
> Wear a suit and tie to an interview
That's a personal test of mine. I have never showed up to an interview without a tie. My dad was a small business owner in a manufacturing sector -- he was the hiring manager -- everything I learned about job interviewing I learned from him and the first thing on his list -- being a previous generation in an industry outside of software development -- was "you wear a tie". There were various reasons given for this. Maybe its the area that I live in, but I've never had difficulty explaining away the tie whereas I know of a few folks in the area who, despite the environment being stricly "dress-down", still expect interviewee's to wear a tie[0].
It's easy to write off with a little transparency and careful humor: "Sorry for being over-dressed. My dad was a business owner and somewhat beat into my head that dressing up for an interview communicates that you want the job. Plus, I love Jerry Garcia ties and have far too many of them for how few opportunities there actually are to wear a suit." Nobody wants to be judged negatively about their appearance, but we tend to make sweeping judgements on that single variable alone -- by adding a little additional information, you eliminate the rabbit-hole of "is this guy going to be a rigid pain-in-the-ass about everything because he insists on over-dressing for an interview?" with "he's actively trying to make a good impression"
Another thing that tends to get lost in the whole "are they a good culture fit" is "is your culture all that great in the first place?" When interviewing people, shortly after determining that a candidate might actually be able to do the job, we tend to fall right into "Will I actually want to work with this person day-to-day". Someone who doesn't fit perfectly into that mold will cause anxiety. But what if the thing that "didn't fit with my teams' culture" is something that your team would benefit from? At a recent job, I was told that the ultimate decision for every employee being hired fell to the founders of the company in consultation with the people who interviewed the developer[1]. The question we're asked is "How will this person make us better?" It sounds fluffy, but it changes how you think about a candidate -- it says "I'm hiring not just to fill a need, but to bring this individual, along with their life experiences, into a team with the goal of all of us improving."
As far as the "personal test of mine" is concerned, I'm perfectly OK with being passed on for a job where my tie and explanation didn't satisfy the interviewer that I was a good fit. Chances are one of two things really happened (1) I wasn't right for the job for a lot of other reasons, but that's the one that was presented (if any were, at all) or (2) a place that would judge me negatively on something so unimportant is a company I'm going to have a difficult time understanding and succeeding in.
[0] This is stupid bit it happens. It's unlikely to disqualify someone, outright, but at these shops, a tie is a plus.
[1] And after a year of being there, I did a few solo interviews and can confirm that "it's true!"