1) The coach speaks to the kids using the same words and tone if the parents are there or if they aren't. If a coach has to tailor the message and vocabulary based on who is in the audience, be very suspicious. Predators use this same tactic. Don't tell your folks what I just said or else.
2) The coach puts the kids health first and foremost. The coach should never be so preoccupied chewing them out for what happened in the first half that they don't have time to stretch out and get ready for the second half. Stretching prevents injuries. And the coach shouldn't put a kid he just took out of the game for a concussion back in the game just because the team needs a score.
3) The coach is at least as smart as someone in the stands who is watching the game for the first time ever. The ability to make good adjustments in the game plan is key. If you have to get all the way down to 5th string looking for a cornerback who can cover a receiver in man to man coverage it just might be time to consider a different coverage scheme and not just blame it on the kid(s).
4) The coach should use more positive feedback than negative feedback. If he isn't, well than that just means the team hasn't been coached very well and they aren't sure what to do next.
5) The coach doesn't need to use profanity to make a point. Anyone who needs to sprinkle profanity into their speech to make a point doesn't have much of a point to make. It is a litmus test for low intelligence. If the coach needs to use profanity to make a point then he is a dummy.