I've worked with animals for 15 years or so, had 4 years of schooling in animal science and have owned may types of pets and you CANNOT trust them ALL the time. Certain animals you can learn to "read" but not all. Dogs may warn you but cats won't. You are better off always NOT trusting. Now I do not mean be afraid all of the time, but always remember that they COULD possibly turn on you at a moments notice.
And for heavens' sake, DON'T trust all humans!!!!
Sorry to be so harsh, but experience talks.