Real Dirt and Magnetic Particles

[faraway]

Maybe there is a good reason to use alcohol as a wetting agent! Kills any critters hiding in the dirt?

Or they call in all their buddy and have a wild orgy on your layout...

I guess I should bake all the dirt I have collected, eh?

Yes, that is generally recommended.

The magnetic particles are very small, like dust. It would be easier to pick them from motors etc. if they would have at least the size of ballast.
I am not sure if I would like to take the risk to have magnetic dust on my layout. You should be very sure to have a method to sort them out with an electric magnet.