Ok.
-The fact is, if the animal doesn't mind(and a non-abused trained one really generally doesn't mind), why is it a bad thing?
How can you tell if they mind or not, can you talk to animals? No? Oh well.
-Is training a dog to fetch is bad? What about training a horse to be ridden? A chicken to play tic tac toe?
That's different, is a form of affection, you are not using it to gain money.
-Also if "living beings should never entertain" is true, then what about humans? Is a dude doing non offensive stand-up comedy a bad thing?
It's not a bad thing as long as they are not forced to do it.