The question should no be so much, "Would my dog be good for this?", as it should be "Are my dog and I both trainable or trained well enough to go through the process of becoming a therapy dog team?"
You dog can be small or big, young (at least one year old) or old, exuberant or quiet; what's important is that your dog be able to obey basic obedience commands such as sit, down, heel, and is in your control around unsteady people and walkers.
The same can be said for the handler of the team. She can have lots of types of personalities. Some people are quiet and reserved, some more boisterous. What is important is that you are able to train your dog to obey the basic commands, that your dog has been very socialized, that you are in control of your dog, and that you are able to use your dog to reach out to people and connect with them regardless of their particular impairment or need.
So, there is no particular personality of dog or handler that is required. I know some very quiet, but good teams who speak very closely and quietly to the residents. On the other hand, some members are known to boisterously get everyone's attention in a dining room to watch their dog do tricks. What is important is that the therapy dog team use whatever type of personality they have to make the most effect.
While a very wide variety of personality types and sizes of dogs and teams can be successful, there are of course expectations for joining. Love on a Leash requires prospective Therapy Pet team members to go through a Certification process which ensures that the teams are safe and of good quality. This process consists of passing the Control Evaluation which tests obedience and temperament, then putting in some on-the-job training under the tutelage of an experienced GCLOAL member.
Not everyone completes the process. Prospective members, those who see us in the community while we are working and express an interest in our work, only see the outcome of the hard work. Our members have earned that blue vest and patch. They keep earning it too, every time they make a visit.
I was reading a Facebook meme of some sort recently, something sappy, about wondering when you die if your life had made a difference. I think for me and our GCLOAL members that's easy. Every time we sit and talk with someone and we all enjoy the conversation and shared dog memories, that is a difference in someone's life. And it's a give-give situation. We give, they give back, then karma gets in there, and probably some kismet, who knows, but in the end, yes, a difference was made.