Whenever you have to use libraries written by someone else, you're in that danger! Most languages at least spell the basic things right, but just now I've got to work with a huge freezer management system that has things like getTempratureInCentigrade and getAliqouts. (Not that I knew what an aliquot was either when I started, but when something forces you to spell something consistently, it's difficult to imagine nobody noticed it was spelled wrongly on at least one occasion that they had to type it themselves...)