corvus
spiritdogs
since dogs don't often approach frontally or present the front of their bodies unless they mean business or are socially inept.
Okay, not to pick a fight or something, but I totally disagree with that. In fact, I rarely see dogs that DON'T approach front on. People are always saying dogs don't do that and I'm telling you they do. All the time. Some dogs don't like it. Most are thoroughly fine with it. Both my dogs are very well socialised and they always sniff around the face first before they do anything else. Kivi is still a pup in his head, but he is neither socially inept nor does he ever mean business. He always approaches front on screaming submissive signals. Penny is certainly not socially inept being 13 years old and seen just about every dog personality there is. She doesn't approach much anymore, but when she meets a dog for the first time it's always sniff at face, then circle and sniff at butt. She has very little interest in picking fights. My mother's two dogs are the same. They don't pick fights, they are very comfortable around other dogs and well socialised, and they at least sniff in the general direction of the other dog's face before doing anything else. They all get as close to touching noses as the other dog is comfortable with. It never starts a fight or gets another dog upset.
Most of Kivi's dog park pals will charge up to him at a gallop and screech to a halt right in his face. People are always saying that's rude, too, but he doesn't mind. Penny does, and the dogs that behave that way don't do it to her. Sometimes I wonder if we know very much at all about dog etiquette. I am beginning to think it doesn't exist. Different dogs have different styles. A polite dog is one that adjusts their behaviour in response to the signals they are receiving to avoid tension. I reckon it's got nothing to do with some unwritten book of dog manners.
Sorry to hijack. To answer the OP, I think ignoring is the best course of action. It tells both your dog and the lunging dog that there's nothing to be concerned about. One thing I've learnt from wild animals is they will often ignore you right up until you start looking at them. They are so leery of interest from someone.
Yes, they do it all the time if they are socially inept. Let me clarify - sniffing about the face is NOT what I consider a frontal approach. To me, a frontal approach means that the dogs are making direct eye contact and facing one another, not averting eyes or making any circular moves with their bodies. That body language is threatening. And, just because most dogs "don't mind" being approached that way does not mean that it's normal greeting behavior - all that means is that most dogs are more or less subordinate and don't elect to cause a ruckus. They simply use distance increasing signals or appeasement signals that thwart a real attack on the part of the approaching dog. If you ever have a dog approach a dog that doesn't think it's ok, watch out. Also, on leash greeting behavior is often not what you would see if the dogs were free to move about.
Actually, we know quite a lot about dog etiquette (great book on the subject by Barbara Handelman, for anyone interested: "Canine Behavior - An Illustrated Handbook", and also Brenda Aloff's book on body language.
Behavior such as you describe at the dog park is not necessarily rude, since, as you say, it is coming from known "pals" who have already figured out your dog's M.O. And, I get the same thing at our play groups - dogs figure out very quickly who they can and can not be so bold with. If they try the same thing on my Sioux or Sequoyah that they try on the eternally bubbly Labs, they quickly get told off Aussie style.
As we know, too, some very reactive dogs will react to ANY approach, even an approach from a respectful language-savvy dog. And, some dogs will NOT react, no matter how rude the greeter is.