Boxes are sometimes torched if someone had American foulbrood,....not the frames, these would get burned for sure, I suspect if torching was done then foulbrood was there
and I wouldn't risk taking any equipment, including boxes.
Paint on the bottom board should be fine.

If you can't trust a beekeeper, who can you trust? :(

I'm truly bummed.

Oh - Konrad, thank you for your post. You probably just saved me a world of grief.

No problem...anytime a new bee keeper is taking on this hobby
new equipment should be purchased. This I learned from our
bee keeping club....glad I did. About 6 month before, a friend,
whose dad used to keep bees, a swarm took home in one of
he's old equipment and gave it to me.
This hive dwindled down soon, to find out it had American foulbrood,...I burned everything.