It doesn’t take long for mold to grow on empty beer bottles. Considering beer bottles get returned for a refund, you have to assume that the brewery will make an effort to reuse as many as possible.

I toured a brewery once and they showed us the big industrial bottle washing machine. They said the bottles get scanned for cracks using a laser, and rejects obviously get tossed. The question is: what about mold, which adheres quite well to the corners of the glass? I wonder if the laser also detects bottles that didn’t get clean. Or if they just figure the temps would kill everything and just be considered safe enough from there.