"Wearing brown could cost you your job"

No one actually gives a fuck unless your whole attire just doesn't match, then maybe you'll get some playful ribbing. 

Maybe they're inappropriate in London but nobody in the US gives a shit

To be honest so few people are going to say anything about a such a minor thing as a wardrobe, unless completely inappropriate, due to possible complaints of [interest -ism here]  remarks 

Sounds like London.

Brown suits shouldn't be in banking. Brown shoes should be. Ox blood and tan can both look very nice.

In either case, no one gives a shit. One of my vps wears sneakers in the office when not seeing clients.

Also caring what the intern wears is like caring how your toddler is dressed.

What firm?

Brown shoes and belts are gross my guy

This is the only acceptable brown

For USA

from most to least formal, all are acceptable in office depending on situation. ie client meeting you should still to navy suit black shoes 

navy suit black shoes (the safest option, most recommended for interns) 

(dark) grey suit black shoes 

navy/brown shoes or grey/brown shoes / any other non outlandish combo 

Back when going to the office was a thing, the brown Gucci Jordaan horsebit leather loafer was my brown shoe of choice. I'd be interest if someone thought that was a bad look? But as an earlier poster already said, just make sure the shoes and the belt match, and you're all good. Don't be wearing brown shoes with a black belt. And don't wear brown shoes with a black suit. Check that, don't wear a black suit, period.

My MD used to say "No brown in town"