Originally Posted by
CommuteCommando
The last charity even I went to WD40 actually had a booth. They apparently have a bike specific lube. I suspect it is a different formulation that the original WD40, which is good for freeing seized stuff, but was never intended to be a lubricant. It was originally marketed as a metal preservative. Spray it on bare metal, the solvent evaporates and leaves a film that protects it from moisture. Same thing happens if you try to use it as a GP lubricant.
WD-40 isn't magic. It's light oil in deodorized mineral spirits (kerosene, essentially). The film that's left is oil. it's not the right thing for any job, but it's hardly awful. It doesn't make a good lubricant because the ratio of oil to solvent is too low, but it's unlikely your coworker got enough into the parts of the chain that need lubrication to matter.