Work, as in execute a command, not washing dishes or cleaning toilets. Will your dog readily "Sit" or "Down" or "Come", etc., if somebody else gives them the command?

I've really been working with Gully on "Sit" and "Down" and "Watch Me" for puppy class, especially "Down". I want a really fast "Down" for agility, so he's the only dog in class that can go straight to a "Down", without sitting first. However, when the instructor gives him the command, he won't do it for her. She's even tried to make sure she's using the same hand signal. I can't figure out if he doesn't understand, when she gives the command or if he feels she's not the boss of him, so he doesn't have to do it for her. I'm leaning towards the boss theory. Luckily the instructor's seen us working out before class around the store, so she knows he's not stupid.

Oz is a lil' bit like this too. There's only select people, who he'll work for. Just curious if anybody else's dog is like this.

Par...