The time I found a wasp nest in my recycled lumber!
I was so proud to score some old oak beams from a demo site for a green cabinet job. When I started milling, a whole family of wasps flew out! Had to stop everything and deal with that mess. Still, the cabinets turned out great, and I saved good wood from the landfill.
You think the hassle was worth it just to save some wood? That sudden danger (wasps are no joke) and work stoppage sounds like a big downside to me. I've seen recycled lumber hide nasty stuff like old nails or rot you don't find until later. The small win of reusing material doesn't always beat the cost and stress of fixing those surprises. Sometimes new wood is just the safer, smarter pick for a smooth project.