This mode uses UV light with the Shark's built-in camera to spot stains that it needs to come back to and scrub. It doesn't stop and scrub these during its initial clean; it'll finish the primary mopping job, go back to the base to refresh the mop pad, and then announce it's going back out to attack stains it spotted. (It literally announces this out loud from the base's speaker.) The UV Reveal uses a back-and-forth mopping style that Shark calls HyperSonic Mopping to truly scrub at a stain, rather than just passing its mop pad over it. The Shark also has a single long pad with a shape similar to half an oval, covering the entire front third of the vacuum, and it will agitate that pad to remove the stains it homes in on.
Courtesy of Shark
I tested its abilities by spilling some maraschino cherry juice around my house. I let the spills dry before I ran the vacuum; the cherry juice left a faint red sheen, so it was easy for me to see whether the spot was gone or not. The Shark was able to clean up one stain with its initial pass, but it came back for the second spot after it returned to the base to scrub it away. It's also scrubbed all kinds of spots in my home where I wasn't surprised to learn there were stealthy stains, from the orange juice crime scene to the space around the cat's food station and floor where we're most likely to stand and cook in the kitchen.
If you're curious what the vacuum is doing, you can usually tell by the lights. There are LED lights on the side of the vacuum that flash a deeper blue to show it's searching with the UV light for stains, and the vacuum's light also flares blue while it scrubs stains away. Shark says it did this intentionally so you can easily see your vacuum and understand what it's doing.
Floor Report
Photograph: Nena Farrell
For a robot vacuum and mop that's got special features for hard floors, my husband and I were both impressed with how well it vacuumed our living room rug. My husband actually thinks the rug felt cleaner and fluffier than when I vacuum with a Dyson stick vacuum. The Shark fearlessly pushes against the grain of my rug as it chugs across it in a way my stick vacuums tend to resist, which gives the rug a more fluffed-up feel.