system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does garlic smell good to us when it’s cooking, but as soon as it’s on someone’s breath it’s revolting?
gpt
Garlic's pungent, but generally pleasant smell is due to a variety of sulfur compounds.  As these are broken down by bacteria and our digestive systems, these sulfur compounds convert into much less pleasant smelling ones.

This is only partially what makes garlic breath so pungent.  Some of the metabolic products enter our bloodstream and are subsequently volatilized through our lungs.  This is why no amount of mouthwash, brushing your teeth, or chewing gum can get rid of garlic breath (these only mask it temporarily).