It's hard to see in the pictures, but this bit twists in the normal direction for most of it's length, but near the bottom, it twists backwards, then back to normal again.
DSCN3956.JPG
It's from a set of low priced brad point bits that I've had for a couple of years. I've probably never used this particular bit before. I checked the other ones in the set and none have the same problem.
How are drill bits made? How could this happen?