This drives me crazy. It's pure pseudoscience, and I hear it from people who should know better. Scientifically, we have very little idea what chemicals are actually behind different subjective feelings/moods/whatever. Everyone would love to believe that the brain operates in a simple, intuitive fashion, with one chemical for joy, one chemical for sadness, one chemical for anger, etc., but the reality is way more complex and nuanced.
For example, even something well-studied like dopamine, which has been strongly linked with the brain's addiction circuitry, doesn't necessarily stimulate any sort of direct pleasurable feeling as people often infer. It seems to work in a much subtler way, modulating learning, attention, and goal-seeking behavior. A recent study found that it doesn't even necessarily spike when good things happen, but tends to increase in response to unexpected events, good or bad.