They are sensible enough to disappear when the play gets to rough or does not go in a way they expect it should. I have never heard a Pug growl in earnest. I managed to teach one of ours, Missy, to growl when we played tug of war with a toy, and Padi has been known to growl occasionally when he spots another dog on the street. But their growl is not the type we associate with a dog showing its temper. It's more of a whimper with an attitude.
Pugs are very loving and loyal friends.
Padi, for example, is definitely a daddy's boy. He willingly spends every moment he can with me rather than Anne. That is as long as Anne is not in the kitchen cooking something. His loyalties, no doubt, are directed at being fed by any and everyone. They, without question, love food of all types and quantities.