I mean, like, you would think the substance bro brings to the table would matter more than his duds 'n' presentation.
The first ordered lunch and wine, in the most unconsciously casual, elegant way. The second then tried to imitate that manner, failing pathetically. I.e. the clothes didn't take away the upper class manner, nor bestow upper class mannerisms.
It's hard to fight your upbringing.
Put them on the floor of a blacksmith shop and you will see them get nervous.
Put them on the floor of a McDonalds in a questionable neighborhood -- that's where they'll get nervous.
Your comment reminded me of a similar experience of mine, but in reverse.
I was washing my hands in the restrooms at work, and decided to drink some water. I bent over, cupped my hand and started drinking.
At this moment, a guy went out of another stall and walked up to the sink next to me. He was some sort of manager, I guess, because he'd always be in a suit when I've seen him around the office before. When I got up, I saw him drinking water the same way I did, only he was failing to get much of it into his mouth. :-) Obviously, this was his first time.
People are really good at convincing themselves that things are just so.
tech is somewhat famously informal; so replace the black hoodie or conference t-shirt with: a shirt, tie and button-down vest.
Despite perhaps looking nice, it would undoubtedly look very out of place, you might even not trust the person as much.
But we all have implicit biases, and it wouldn't be my gut feeling to trust a person who does not present as 'one of my group' like this.. even though I'm aware of the bias.
You can definitely dress in a way that doesn't look that much "lower" to an outsider but looks very wrong, and, gasp, poor to someone in-tune with tech worker fashion. So it's not just dressing too nice that does it, and hell, for that matter you can spend about as much as the cost of an on-sale Brooks Brothers suit buying a "tech shabby" outfit[0], with results that will definitely be appreciated by many your fellow tech workers, or simply overlooked by others in a way that Red-State-Working-Class or suit-and-a-tie won't.
[0] The aforementioned Red Wing Heritage boots are north of $300 for most models, full retail, and check out Arc'teryx and such for how expensive trail shoes can get ($150+, and they're not the most expensive brand), but even something like Danners are pretty pricey compared to what normal people buy for shoes; dropping $200 on a hoodie and rain layer is easy (again, go for expedition-clothing sorts of products to run up the price tag but also the tech worker cred—$300 just for a paper-thin rain jacket isn't even the top of the range); $80 merino wool hiking shirt ("I just love how it keeps me dry, but also I love talking about merino wool with other people who know how expensive it is"); and shit, jeans, sky's the limit, you can hit $200 on those while still just "buying more quality" and not even in just-paying-for-the-label territory yet.