the craper the economy in said country the better the deal you will get changing your money over there.
walk into a bank in uganda and go to change £10K sterling into shillings, you can jump a few hour que, negotiate the exhange rate and get cups of tea, then they offer to escort you with armed gards to wherever you want to go.
the armed gards are a bad idea tho, got to attract loads attention and they have sh!tty old enfiled 303's that look like they'd be more effictive if you used them as a stick