Unorthodox describes something that goes against the usual ways of doing things. Instead of describing yourself as a terrible speller, you might instead proudly refer to your spelling as unorthodox.
The adjective unorthodox originally referred to religion, specifically to a person or practice that went against the traditions of a particular belief. The Greek roots of unorthodox are orthos, or "right," and doxa, or "opinion." So someone whose beliefs are orthodox has "the right opinion," while an unorthodox person does not. The definition has evolved so that unorthodox's meaning is closer to "unusual" or "innovative" than just plain "wrong."