This topic may have died but its one dear to my heart!
No, I don't think it is ever acceptable, but its understandable when handlers over-hype dogs believing they have to be hyped up to a) succeed and b) enjoy themselves or c) think they will be stopping the dog from enjoying agility if they try and stop the dog getting over-aroused.
In reallity its a skill like any other...ie the dog needs to learn to be motivated, fast, focused and enjoy agility *without* losing the plot. Dogs that are constantly over-active, bark hysterically, bite, crash thorugh jumps and generally behave like headless chickens aren't 'enjoying' themselves imo...they're seriously over-excited and probably very stressed! Usually because they don't truly understand what is being asked of them, have poor impulse control (needs to be taught away form the agility class using toys, the 'real world' etc), poor obedience without lots of physical coercion and the handler lacks the skill to teach 'boundaries'. What usually makes the stress (and that hyperactivity and biting) worse is the handlers get stressed and angry and start trying to correct the dog...but usually inconsistently becasue they don't really want to do it, or get so caught up in the training they see it as a 'side issue' and don't want to have to deal with it.
If the classes view it is as acceptable and OK to a) let such dogs reach that over-stressed state and b) let it be physically possible for the dog to bite other dogs (and it is COMPLETELY the handler's responsibility and down to their lack of training and control, not the dog's fault) I'd change classes. A pity...but its not worth the risk imo.
