They choose you; it's canine-human speed dating for a match. Something in those abandoned sweethearts can sense when someone is their match, and they turn on the charm.
You’re absolutely right. My dog (a shelter rescuee) put his paws on each of my shoulders and pulled me towards him and hugged me when I knelt down in front of him to say hello the day that I went to my local shelter to find a new best friend. It was as if he was saying ‘where have you been? I’ve been waiting for you to take me home’. He picked me that day. We had 14 wonderful years together. He was the greatest dog ever. Someone had left him tied to a tree before he was rescued and brought to the shelter. I don’t understand how people are so cruel to animals. My dog had a gift of making people smile. If everyone had a dog like him, people would be much happier, I am convinced.