I have a Cocker Spaniel. The english variety are quite different both in size and personality, so I don't know too much about them. I've had two Cockers and both did not go after smells. My Cocker I had a few years ago did go after squirrels and chased cars. My Cocker I have now is very good off leash and stays with me for the most part.. especially when we aren't in the city. He gets distracted by all the people and cars, so he can only go off leash in the country.
I think it depends on the amount of training with this breed.
The English variety is still used for hunting today, and I've heard they are pretty good hunting dogs. You'll find for the most part the American variety has gotten their drive for hunting bred out of them as mostly used for family pets. Many people think the ECS is the same as the American variety and assume they're not good hunting dogs, when they actually are.
Both breeds are very charming dogs and they LOVE to please people, more than many breeds. They're actually very sensitive to discipline, I have found, and do not do well with yelling or slaps to correct them. (Although I agree no dog should be yelled at or slapped)
They are extremely prone to ear infections, which if not treated will easily lead to hearing problems and sometimes deafness.