|>>|| No. 6014
Black is just a bit too formal for business casual, particularly the more casual end of business casual. You'll probably get away with it, but it looks a bit half-arsed to anyone with an eye for it. Black is usually OK if you're wearing dark tailored trousers and absolutely fine with any suit.
"Never trust a man in brown shoes" is just a daft old saying. They used to be uncouth about seventy years ago and are still seen as chavvy in the City of London, but the City has a lot of unique idiosyncrasies that mainly serve to discriminate against non-Etonians. If you're wearing a suit, never wear shoes that are lighter than the suit. Dark brown shoes are fine with medium grey and navy suits, but wrong with a charcoal or dark navy suit. Black suits are for funerals only.
A dark mahogany brown with a hint of red is fine and a deep oxblood is usually OK, but a lighter orange tint looks naff. Look for variation in colour and texture - cheap reconstituted leather has a uniform appearance that natural leather doesn't.