system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can you wash germs and dirt off your hands but not some smells?

Your hands stay stinky even when they're clean. Such as a fish smell lingers on the skin hours after fishing and labourously washing hands. Why is that?
gpt
Germs are thousands of times bigger than smells.

For a real ELI5: If you spill marbles on the floor, you can "wipe" them into a pile. If you spill flour, there's almost always a trace left behind unless you work very hard. Because the flour particles are so much smaller than what you're wiping with.