To the best of my knowledge head hunting is almost never discussed by football media or the NFL. It's a dirty little secret they seem content to ignore. Maybe it will go away?
There have been a couple of highly public instances over the years when the secret bubbled up and had to be addressed. One in the 80's I think and then Bounty Gate where saints coaches and plyers set up a monetary pool for any player that knocked Brett Farve or other specific players. Sean Peyton took the fall with just a one year suspension and it was never talked about much again. In addition the Players Association, incredibly, depended the players involved and got their suspensions dropped! They were trying to injue other platers!
A minor example occurred in the wild card playoff round where Abrams, a Seahawk defensive back, pulled on Debo Samuel's injured leg after the play was over. No flay and no fine.
In my mind the NFL encourages head hunting