Warning officials?

[7Rock]

How do officials feel if a coach comes up to them before a game and lets them know of a tendancy a team has for doing something that is illegal, that they have observed in game films?

Two examples I can think of are:
a)A team try`s to neutralize a good kicker by sending a headhunter after him on kickoffs.
b)a running back has a habit of grabbing tacklers face mask while straight arming.

Does this offend officials or does it help them?