Also, if the dog begins to show any typical stud behavior such as marking territory or being obsessed with looking for girls and ignoring commands from his owner when other dogs are around, then neuter ASAP. Males showing dominance issues should be neutered earlier too.
May I offer a behaviorist perspective?
First, I totally agree that if a dog owner can not prevent accidental pregnancies or unwanted behaviors, then neutering is a good solution to consider.
However, if it is a behavior that is the problem, then I recommend addressing the behavior with a program of exercises to change the behavior.
Behaviors such as mentioned above can be modified with the right program for owner and intact dog.
Ignoring commands is a behavior that can be modified by building a relationship with your dog that makes you more interesting than any other dog!
Primary rewards (High value treats) can be paired with emotion, like tone of voice and smiling, to encourage the dog to pay attention to you regardless of the distraction.
If the dog thinks you are the "meal ticket" and the most fun, then your dog will find his way to you very quickly. Attention will be on you, if you have built a strong relationship with any dog, even an intact large breed dog!
"Dogginess", or more interest in other dogs than the owner, can be addressed by limiting time spent interacting with a second dog in the family.
Again, if the intact dog is accustomed to looking to you as the leader, he will take your leadership cues in distracting situations. If it is accustomed to looking at you as just a pack member and another dog or itself as leader, the dog (female, spayed neutered or otherwise) will not likely look to you for leadership cues in public or new situations.
BTW "leadership" to me means rewarding your dog when it dogs something right and removing something it wants when it does not pay attention to you. ie.) Time outs -removed from pack and fun.
Typical male behaviors like marking objects, scratching the ground, smelling the ground and licking lips are normal, hormonal responses.
It seems the appropriate response to behavioral problems for the pet owner, such as 'dominance issues", is to train, change or prevent the behavior.
It reminds me of the expression, "Don't throw the baby out with the bath water".
Undeniably, the best reason to neuter is to not contribute to the overpet population problem.
I have worked an intact GSD with an intact mastiff in agility who display normal male behaviors, but their attention is on the handler and the handler has control of the dog.
These dogs have trained to have a strong recall with distraction, sit/stay and have a word associated with timeout like Leave it.
NOTE: For any help changing behaviors, seek a professional who has experience in kindly and gently changing behavior-please!