Why painted?

I saw this a few weeks ago. The property card listed the fire damage and was about 20 years ago. The house has went through a recent remodel not related to the fire. I never asked the agent or the buyer about the fire it was just my inside knowledge. When I looked in the attic I saw the rafters were “painted” and it does not really look like typical paint. But other than that attic was in great shape. I left it alone as there were no smell or other issues but I was really curious about fire damage and really tried to find anything that said FIRE! but I guess they did a good job fixing it.