I have a bunch of 4" Keitech swimbaits and most of them have crooked tails.  Not sure why this happened since I never even took them out of the package.  Anyways, I am wondering if I need to straighten them out by the boiling water method.  Will the bent tails affect the action?  Has anyone experimented with this?  Thanks for any advice.  

Nah. Fish with em. If you don't get any bites and convinced it's the action (and not location / timing ) then boil the tails... Super easy but I usually only have this problem with stiffer plastics like zoom.