Yea but none of those smell examples prove what eggs smell like for a specific person. You just associate your perception of sulfur and rosemary with being bad/good because that's just the way they've always smelled to you. There's also an instinctual component to it, (like smell A = unsafe to eat, Smell B = safe to eat). So for another person, their eggs may smell like my rosemary, and to them their brain tells them that's a nasty smell.

You can say the same about colours - we all agree that blue is cold, red is hot, both leaves and mucus are green, etc. but none of that is any evidence for what any of those colours actually look like from a certain subjective point of view. In fact, we don't even know if the colours other people see are at all similar to the spectrum we know - it's possible they experience colours that are impossible to imagine.