I was not too pleased to see an opponents coach giving some hassle to the ref at a recent match of ours. The lads are there to enjoy not to see bickering and whinging. The amount of times we have to play against poor standard refs at other matches and not one of us hassles the ref. He has a hard enough job as it is, and the refs decision is final after all.
Good forum by the way

Quite right too. The last thing we need is for the game to go the way of the round ball...

I've had several issues with opposition coaches refereeing, but rarely with coaches on the sidelines... I've noticed that occassionally parent's, more often the mothers [not being sexist, just honest], over-react when their little Johnny is manhandled. Also certain clubs are notorious throughout the age groups for issues with their refereeing not always being 'fair'...
Though the worst I've come across is when young kids are clearly coached in dirty play or to be overly aggressive. Don't get me wrong, there is room on the field for aggressive play if it's channelled and used correctly. As coaches we have a responsibility to teach the kids how to use controlled aggression appropriately and not to overstep the mark into aggressive behaviour.

But in my view, regardless of the refereeing, coaches should bite their lip, unless there is a risk of injury to a player, in their role as a good role model to the kids...