Ok so my question then is has there been a case where two well socialized dogs that understood canine body language within a reasonable degree ended up fighting?
I would think so. Dogs have personalities, moods and emotions similar to people, though their moods/emotions tend to be less complex than humans according to what science has discovered so far. So just as a generally well-balanced, friendly and socially adept person can have a bad day and end up arguing or fighting, so can dogs.
Are most dog fights from poor social skills and lack of socialization? What else causes them?
I think most dog fights are from human mismanagement, at least as far as 'pet' dog fights are concerned. The dogs may be communicating just fine, but humans misinterpret or insist on two dogs interacting when they've made it as clear as they can that they don't care for each other. Or humans who accidentally teach their pet dogs that they need to 'guard' their valuable items, whether it's their dinner dish or a toy. Take away the human element, and I think most pet dogs are much more able to avoid having conflict escalate to an actual fight.
This isn't to say that fights won't happen, of course. Food resource guarding is a natural behavior of dogs and even more natural when they aren't being fed regularly. Food is worth fighting over, so in a dog's natural state I would expect to see fights happening over food even if exemplary dog language is employed. Same with mates, or territory.
The more confident a dog is, the less likely that dog is to get into a fight under any circumstances. My dog is very fearful of new things, whether objects or dogs; if he sees something that concerns him, he stands up straighter, raises his tail and head and watches closely. Some
people have identified this stance as 'dominant' or 'protective'; in reality, it's pretty damn rude at least as far as other dogs are concerned. A confident dog, on being approached by my dog in such a manner would turn his head and avoid eye contact, perhaps pretend to sniff something on the ground, and generally work to de-escalate the situation. A less confident dog will respond in kind, and engender something of a Mexican stand-off.
In my opinion, trying to see dogs as anything but individuals and interactions as separate events is a mistake. If one were to see my dog Boone, and my BF's dog Tara interact outside the house, they'd probably think Tara was dominant, if they were inclined to that line of thought. She approaches him at will, she sniffs him even though his body language suggests he doesn't really like this, she puts her head over his back when trying to entice him to play; she chases him away from the humans especially if she thinks treats might be forthcoming. But inside the house, one might see that Boone is in 'in charge'. Tara moves out of his way, and he can keep her out of the bedroom and off the bed with just a look; he's taught her not to 'finish' off his dinner for him until a certain amount of time has passed; as near as I can tell, that's 20 or 30 minutes.
What I think is going on is that Tara has poor dog skills and is somewhat rude; Boone puts up with this when they are out playing because he lives with her and accepts her as she is, and in the grand scheme of life, these things aren't worth fighting about. However, the two or three things he wants he *really* wants, and Tara has learned to respect that.
I think the big mistake in looking for signs of 'alpha' or 'leadership' is that people will tend to put a dog into a role that just might not be accurate. If someone has an inaccurate view of their dog, then they may make serious mistakes in terms of training and interacting.