adj. As used by hackers, implies that some system, program, person, or institution is sufficiently maldesigned as to be not worth the bother of dealing with. Unlike the adjectives in the cretinous/losing/brain-damaged series, 'evil' does not imply incompetence or bad design, but rather a set of goals or design criteria fatally incompatible with the speaker's. This is more an esthetic and engineering judgment than a moral one in the mainstream sense.
"We thought about adding a Blue Glue interface but decided it was too evil to deal with."
"TECO is neat, but it can be pretty evil if you're prone to typos."
Often pronounced with the first syllable lengthened, as /eeee'vil/.