Old scratch is buggy - when using his normal attack most of the time it poofs even when its on 9 clean squares with just foe's on them. It has about a 50% fail rate is this intended? if you can you add a fizzle that would show up? Normal attack is 9 squares because its improved area x2 anyone else notice this?
As Ratbeard said, Old Scratch's (and any witchdoctor/companion that can hit multiple with normal attacks) attack ignores the dodge rating of the target. This makes him great against high dodge enemies.
Next time you use him count the number of times he does hit rather than the times he fizzles. You may be surprised at how much he actually hits.