Society has really pushed the idea of "You have to socialize your dog every chance you get." As a result, some dog owners feel the need to have their dog meet and greet every person and dog they encounter while out in public and I think this is a mistake.
Let me first say I understand the importance of socializing dogs. I think dogs having some dog friends in their life is important. As a trainer, I also realize the importance dogs have in helping other dogs in need of behavior modification and rehabilitation. I think there are plenty of simpler and healthier ways for dogs to meet other dogs other than through random leash walks, such as: dog social groups, family and friends with dogs, training groups and programs, organized pack walks, doggy day cares, etc.
My own personal pet dogs have a plethora of doggy friends (mainly due to my board and train programs); however, when it comes to walking past strange dogs in public, I never allow my dogs to visit and here is why:
1.) I simply don't know the other dog(s). I want to know who my dogs' friends are just like a parent wants to know who their kids' friends are. I do not want my dogs to visit in close proximity (close enough to be bitten) with a dog that I know nothing about. The ramifications of a bad greeting are real and I want my dogs to be safe.
2.) The average dog owner simply cannot control their dog, especially during a stimulating situation like a dog-to-dog greeting: My personal dogs appreciate strange dogs jumping all over them as much as I appreciate strange humans jumping all over me. I just don't trust that the other owner is going to be able to control their dog and that sets up a recipe for stressful energy and stressful energy brings the potential of bad things happening.
3.) Unfair and unrealistic expectations: I feel it is a bit naive and unfair to expect a dog, even a very friendly dog, to get along with every dog it ever meets and this unrealistic expectation could potentially set a dog up for a bad scenario. People do not like and/or get along with every person they meet, so why should we expect our dogs to?
4.) Aggressive Dogs & Dog Fights: As a dog trainer that constantly gets phone calls for help, I can assure you, unfortunately, that there are dog owners out there with dog-aggressive dogs and they are purposely allowing their aggressive dogs to meet other dogs while out on leash... in hopes their aggressive dog just "gets more used to dogs and makes some friends." These owners are subjecting innocent dogs (and owners) to fights. Not all aggressive dogs are lunging and barking and pulling when they get near a dog. Some are VERY quiet and VERY still before they bite. Many times tails are wagging when dogs bite (tail wagging is NOT necessarily a sign of "happiness" it is a sign of increased arousal- all depends on the way the tail is wagging).
5.) The potential of creating too much of a "social butterfly" dog. Generally speaking, I do not want to create a "social butterfly" dog that becomes "Unglued" with excitement every time it sees a person or dog. Owners that allow their dogs to visit with person after person and dog after dog while in public are most likely going to create a social butterfly dog. I personally want my dogs to be able to ignore environmental stimuli when we are out in public. I like it when my dogs will sit, lay down or walk quietly and calmly while in the presence of people and dogs; not get all jazzed up and pull like hell every time they see people or dogs because they think its social hour.
Lets socialize our dogs and have fun with our dogs but lets do it smart :)