The best teacher is experience. Minor things like having your arm at 43 degrees instead of 45 degrees isn't a big deal, and in the grand scheme of things the most important is whether or not you can apply it successfully. Outside of that nothing matters as to how it "looks".
"I don't know if anyone is known with the art of "sitting on your couch" here, but in my eyes it is also to be a martial art.
It is the art of avoiding dangerous situations. It helps you to avoid a dangerous situation by not actually being there. So lets say there is a dangerous situation going on somewhere other than your couch. You are safely seated on your couch so you have in a nutshell "difused" the situation."