Right now, my oven looks clean—but when I turn off the overhead lights, it looks like it’s covered in tiny filaments of dust. My kitchen counters, which also looked clean two seconds ago, reveal a spattering of crumbs that I must have missed during the last wipe-down. Every surface in my home, from my desk to my coffee table to my piano, reveals its hidden gunk as soon as I dim the lights.
What’s going on here? The same thing that is currently leading me to believe that my laptop screen is perfectly clean (when we all know that as soon as the screen goes dark, it will reveal every dust mote and fingerprint). Bright light washes out certain types of dust and grime, which is great for those times when we want to our surfaces want to look clean—but it also means that cleaning in bright light might cause you to miss some of the finer particles and smudges that are covering nearly everything in your home.
So the next time you wipe down your kitchen after dinner, try wiping it down again with the kitchen lights turned off. (I’ve got one of those above-the-oven microwaves with a light embedded in the base, and that is the perfect amount of illumination to reveal that my kitchen isn’t as clean as I thought it was.) Depending on the way your windows are situated in your home, dawn and twilight might also be excellent times to get in some serious scrubbing.
Or you could just turn on all the lights, look around, and decide your house is clean enough.