You're confusing a societal concept of health for a biological one. Generally speaking, we classify any brain that does not function as expected as abnormal. However, you wouldn't necessarily define that person as "sick" or "unwell," in the same way that you wouldn't call someone with synesthesia or without a visio-spatial sketchpad "sick." It's just not functioning as expected.

People eating spicy food is actually different, because there can be a couple different reasons for it. If it's a case of receptors misfiring and indicating pleasure instead of pain, then yes they'd have unhealthy brains. I think typically spice enthusiasts have abnormal tongues though. Usually their receptors have dulled either due to repeated exposure to spice, genetic differences at birth, or external factors like coal dust.