It’s a fact. Not all dogs like to be patted, at least not all of the time.
Dogs have preferences as to where, when and how they like to be touched. They also have preferences for who they like to be touched by. Just because they love a chest scratch from their care giver, doesn’t mean they want the same from a stranger. Even in the same household a dog may enjoy a particular interaction from one member of the family, but not from a different member. The good news is that it’s easy to ask a dog if they like the way you’re touching them. It simply requires some knowledge of dog communication and attention to their body language.
We need to recognise and teach children to learn our dogs “no” signals. When you approach to pick up or hug your dog become aware of attempts to avoid the impending interaction. If you bend down and your little dog moves away, they probably don’t like being picked up much, let alone hugged. Many dogs tolerate our hugs but don’t actually enjoy them. Some dogs don’t mind a hug from their special people, but don’t want the same affection from others.
Here’s a quick summary of how dogs say “yes” or “no”. Sometimes they say “maybe”. I suspect they are conflicted at times because they want our attention but don’t like the type of attention that they receive. It’s the classic walk away and then come back and then walk away routine. Once we change our approach, a “maybe” can soon become a “yes”.
If you miss the more subtle body language for “no”, the dog may escalate their distance increasing behaviours to become more obvious and effective. Dogs who really find patting aversive (i.e. hate it and can’t wait to escape) may learn to skip the subtle requests if history has taught them that no-one ever listens. When pushed, a dog can learn that growling, snapping or biting are VERY effective strategies to give them space.
Clubs Offering:
Many dogs dislike being touched or patted on the top of the head. All it takes is a quick search on the internet to see countless photos of dogs showing stressed body language while being patted on the head. Body language signals your dog might exhibit are ducking away, lowering of the head, stepping away, putting the ears back, licking lips, or whale eye (whites of eyes visible).
Humans seem to be disposed to want to pat a dog on the head; this is likely for several reasons. A dog’s head is usually the closest part of the dog we can reach. For some dogs, we don’t even have to bend down to reach our dog’s head. Humans seem to mimic this behavior from other humans. Think of a parent lovingly stroking their child’s hair. Children may enjoy this, but most dogs do not.
Humans can also be quite rough when patting a dog on the head, and it may not be an enjoyable experience for your dog. Coupled with the fact that dogs inherently dislike something reaching down from above toward them, most dogs quickly learn to associate a hand reaching toward their head with discomfort or stress. This leads many dogs to become head shy, and they learn to duck out of the way of a hand reaching toward them. 
This can be an annoyance when you have to follow your dog across the room to put on his leash, or even downright dangerous if you need to grab your dog in an emergency and he ducks away from you.
But the good news is there are many things that you can do to prevent head shyness and even give your dog a positive association with someone reaching toward his head.
Don’t Allow Strangers to Pat Your Dog on the Head
Most dogs are comfortable being patted or scratched on their chest, chin or back. Kindly ask that others pet your dog in those areas. If that isn’t possible, try turning your dog to face you, which presents his back to the person who wants to pet him. You can do this by rewarding your dog with a treat every time you call his name and he turns to check in with you. Do this for several weeks, making sure to practice in many different locations in and out of the house and then start weaning off the treats so you can use this technique while out and about. While at home you’ll still want to practice touching your dog’s head because you can’t trust that a stranger will follow your instructions for petting gently rather than patting roughly.