What Are They Actually Detecting?

Is it smell or is it actually microorganisms they're picking up? Yeah, it's very, very, very interesting. I feel like we're going between a deep discussion and a discussion you have after buying stuff at Spencer's gifts. A scientist says just like the detectives today are dusting a room to look for fingerprints, maybe in the future, they'll take a big vacuum and see what microbes are there. It's certainly not tomorrow, but it might be possible.