Interference is the act of an offensive team member that hinders the defensive player's ability to make a play on a runner. The key word for me is "hinders." Did the runner's actions or position force the defensive player to adjust their throw? Did the runner's actions or position force the defensive player to stop prematurely? Did the runner's actions or position force the defensive player to hesitate?
If I'm going to call a runner out for interference, I'd better be absolutely positive that it was, indeed, interference. ASA took out the references to "intent" this year, and that has made the mind-reading game virtually non-existant. However, I will admit that the benefit of the doubt, for me, leans a little more towards the runner.
The rule is clearly defined, but whether or not it was interference is still a judgment call. My judgment is that if I don't see a clear deviation by the defensive player because of a hindering action by an offensive player, I don't have interference.
Coaches teach their players to play dirty? That's unheard of!