The original question had to be edited. I think that the "good work" that the fire department does is seen as protecting its citizens from the "dangers" of books. Critical thought is perceived to be fundamentally wrong in a society where the fire department is needed to extinguish books. Books create thought and a sense of questioning, elements that are not tolerated in the society in which Montag lives. The "sanity and comfort" of the community is threatened by books. It is for this reason that the fire department is seen to do "good work" in its protection of the community.
The significance of this "good work" is profound. Those in the position of power have determined that asking questions and engaging in critical thought are fundamentally bad. These elements disrupt the ability to live in relative comfort. Books are a part of this destabilization and for this reason, the fire department is perceived to do "good work" in extinguishing books. It is within this social condition that Montag awakens and sets the trajectory of the book in motion.