The philosophy of positive training for dogs has been around for long enough, that most people have heard of it. Never say no! Reward, never punish! Maintain a positive attitude at all times! Commands are stated briefly and cheerfully (or with a merry click of a clicker)! Keep lessons short and fun!
Before long it begins to sound like one of those syrupy slogans that have infiltrated our Consciousness. The Power of Positive Thinking! Accentuate the Positive, Eliminate the Negative! If it Feels Good Do It- oh wait, maybe not that one. Turn On, Tune In, Drop Out! (Definitely not that one).
Please don't think I'm advocating the Put the Dog's Nose in It school of training. I am not. I also am, most assuredly, not a strict adherent to the Positive school. The reason is very simple. I live here in real life. And the truth about reality is that sometimes you must say no. In the real world you cannot always set things up so that your dog is good. Naturally, you avoid trouble when you can. That's why, when he was a puppy, you put him in his crate while you took a shower. You didn't leave him in the kitchen hoping he would take a nap rather than chew on the baseboards. Or you put up the baby gate to keep him out of the room before you fill the table with forbidden food. Alas, in the real world sometimes you forget to put up the baby gate. You are rushed because the guests are due and you aren't dressed yet.
Your dog tries to take a taste off the buffet table. Is this really the time to redirect him to a toy? Real life rules! A firm loud NO will get his attention faster than, "here my darling, have a nice pull toy". You want the dog to stop before he dismantles hours of labor and ruins the dinner party before the guests have a chance to. Besides, who really believes that gentle words detailing the wonder of the Nylabone are going to be more attractive to your dog than Pigs in a Blanket arranged in a circle? Startle him! Break his concentration from the thing he may not have! Stop him before he does the bad thing. Say NO.
When he removes himself from the platter of good things meant for others, then you praise him and give him the Kong filled with peanut butter. He'll notice it is a lesser treat. More importantly, he'll notice that you, his Master, forbid him the people platter. That's real life for you. And for your dog.