Carol is getting mixed signals from her dog when in the company of others.
It seems that Pogo, a Labrador mix, enjoys interacting with most dogs, but growls occasionally when she introduces him to a new dog. She wants to know how she can get Pogo to get along with every dog he meets.
Do you want to be friends with everyone you meet, Carol? I doubt it.
Here's my best analogy for this situation: When I'm attending a large party, I enjoy the company of friends and I like to meet new people. On occasion, I'm introduced to someone who rubs me the wrong way. If I don't enjoy this person's company, I quickly find a way to move on to someone else. There are people I might avoid entirely, based on their behavior or antics, and others I might gravitate toward.
As long as I get along with most people, and provided I don't make a scene when encountering those I don't get along with, I think I can describe myself as normal.
Pogo is simply making his own decisions about whom he chooses to become friends with, and you should respect this. You should not force him to interact with a dog if he doesn't seem to be interested in doing so.
Introductions to dogs should be done on a slack leash, and keep in mind that dogs don't usually greet each other face to face. They approach each other from an angle, and usually begin with a sniffing around the genitals.
A growl is a rather polite, but explicit way for a dog to get his message across: "I don't like what you're doing."
Rather than reprimand Pogo for growling, help him out of his uncomfortable situation, and move him away from a dog that he doesn't wish to get to know.
In spite of your assessment of any new dog you encounter, Pogo will always be better at "reading" any dog; after all, they speak the same language.
Pogo sounds like a friendly, social dog overall, who enjoys the company of most other dogs. My approach and recommendations would be different had you described a dog that growled at every dog he encountered, or if his growling had been a precursor to a scuffle. So continue to respect his decisions about who he wishes to have contact with, and help him out of situations where he is uncomfortable -- even before he growls.
Lisa Moore's pet-behavior column appears once a month on the Weekly Pet Page. Write to her in care of LifeStyles, The Modesto Bee, P.O. Box 5256, Modesto 95352.