They are used for drop-shotting. Get that hook to stand staight out from the line.
They do work, even caught fish using them, but I prefer a Kahle hook myself when drop-shotting.
This video clip should answer your questions.
http://www.fishingclub.com/ExtraCon...?id=145488
If the link doesn't work:
Hover the "video" tab
Click "Tips, Tricks, and Tools"
Click video titled "Hooks"