system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are fire trucks kept obsessively clean?

I bike past my local fire station every day, and I see the firemen scrubbing the whole truck fleet down almost every week.  

Other city vehicles (police cars, other trucks, etc.) Aren't necessarily dirty, they just don't have the shimmering glow one sees when a fire truck drives by.

Why is this?  Does the cleanliness add functionality to it?
gpt
Because they have a hell of a lot of time between calls where they are basically doing nothing.  It's exactly the same in the UK, when they aren't fighting fires they're cleaning the fire engine.  Police cars are always dirty because when cops have down time they are out on patrol.  Ambulances are always dirty because they're in constant use.
Source-am cop.