Shampoo and conditioner are usually meant to go together, but there's no law that says it has to happen that way. Some people refuse to use Brand X's conditioner after washing with Brand Y's shampoo, while others show a rebellious streak by mixing things up. Shampoo and conditioner are an especially big bone of contention, since we tend to use them in conjunction. So what camp are you in? And have you ever wondered why you've developed the preference you have?