I said "Thank you!" to a guy who took his (leashed) dogs to the side when he saw me approaching. It was considerate of him.
The people I'm giving a look to, it's not because I am "scared" and need their emotional reassurance. I have that expression because I am *angry at the person*.
Reassuring me about the dog's personality when they are with you, at home, is not helpful to me and makes me angrier.