I don't own a Chihuahua, but have known several. Before we bought this house, there was a Chihuahua in our old neighborhood named Chico. He had been a rescue boy, but was as sweet and calm as could be - and friendly, too!
He was so well behaved, he walked with his owner and she just let his leash drag on the ground behind him. That way, if Animal Control happened by, she could reach down and pick it up, but he otherwise could walk with her with no leash needed, really!