At there was always one who hated men with hats. 
One of the two dogs we adopted from a shelter, also has similar issues. Also, men in work boots, big engine cars driving by, and bicycles. She's got a ton of "issues" that we've been working for 6 years to break her of. Sometimes successfully, many times not. But from this we've been able to piece together some of her history (she was abused and neglected in her previous life before our house).