Bob appreciates practical jokes and community service. It is not enough to simply blow up someone’s industrial ship, steal the contents, and then leave. No, That would be rude, and poor form.
To leave behind dirty freight containers would be terribly impolite. One must make the effort to acquire some Janitors, leaving one behind in each container, with a small pile of Garbage.
Of course, these services are not free, and it would only be proper etiquette to demand the owner of the filthy containers to pay you for the services of said janitors.