Fortunately, off-register printing doesn't happen as often as it did 30 years ago. I remember when I used to see LOTS of fabric that came through like this.
Funny thing is... sometimes the more "mod" fabrics are designed so that some of the colors are intentionally off. You can tell when it's done on purpose, because the same color is off to the right some places, and to the left in others. If it was truly mis-printed, it would be off in the same direction all the time.
I can't wrap my mind around why you would want a fabric that's printed "off", whether by accident or on purpose. So I would never buy any of those! :|