Have you ever taken an invisible test?

There’s a legendary story about 1980s rock band Van Halen that has nothing to do with music. Buried in their tour rider—the requirements document the band gave venues for staging, electricity, sound, and lighting—was a clause demanding that M&Ms be provided backstage. The kicker was that there was a line that specified that every single brown one should be removed.

To outsiders, this looked like peak rockstar arrogance. What kind of jackasses care about the color of M&Ms? For years it was held up as the ultimate example of diva behavior.

But the reality was more clever. At the height of their popularity, Van Halen was hauling nine tractor-trailers worth of equipment into small-time venues where the biggest previous act might have only needed three. Their concerts required elaborate lighting rigs, massive sound systems, and precise electrical work. If something was set up incorrectly, it wasn’t just a bad show at stake. A heavy speaker could fall and crush someone, lights could come crashing down, or faulty wiring could electrocute a crew member. The risks were deadly serious.

Van Halen needed a way to verify whether local crews had actually read the rider carefully and understood the level of detail required. The M&M clause was their elegant shortcut.

If the band arrived and saw brown M&Ms in the bowl, they knew the crew had skimmed the rider, and they immediately ordered a full safety review of the entire setup. If the candy was sorted correctly, they could feel confident that someone had paid attention to what mattered.

This is what I call an invisible test: an unstated, low-stakes check that reveals something crucial about competence, reliability, and character. Invisible tests aren’t just for 80s rock bands.

How Invisible Tests Work

If Van Halen had simply asked a venue manager, “Are you careful? Are you thorough?” the answer would always be yes. Invisible tests work because they are unsignaled. If people don’t know they’re being evaluated, they can’t manufacture the “right” response. This advantage is becoming more crucial as tools like AI make it trivially easy for anyone to generate polished, convincing answers to direct questions. The gap between what someone can say and what they can actually deliver has never been wider.

The minute people know what you’re looking for, they game the system, like job applicants rehearsing answers to cliched “What’s your biggest weakness”-type questions. See also: Goodhart’s Law, the principle that when a measure becomes a target, it ceases to be a good measure.

Other Examples in the Wild

I know people who marry the wrong person, get divorced, and decades later they still haven’t recovered. Choosing a life partner is the most important decision you’ll ever make. In dating, invisible tests reveal character in ways that direct questions never could. Someone looking for traditional values in a partner might not explicitly ask their date to open the car door—that would defeat the purpose. Instead, they simply observe whether it happens naturally. If it does, that’s a glimpse of someone’s default settings, not their sales pitch.

A friend of mine owns rental properties. He told me that tenant applications are essentially worthless. Everyone looks stable on paper and can find references who speak glowingly about them. This is a problem: Bad tenants are the ones who make messes and play loud music at all hours of the night, making the living experience worse for the neighborhood. Bad tenants create hazards; they are the ones who forget to turn off their stoves and leave lit cigarettes around the property.

So he’s developed his own invisible test. When he walks a prospective tenant through a unit, he always takes a casual glance at their car in the parking lot afterward. The backseat, he’s discovered, reveals the truth. If it’s clean and organized, he knows the apartment will be maintained well. If it’s a disaster zone of fast-food containers, crumpled clothes, and random debris, he doesn’t need to imagine what the carpet will look like in six months. He’s already seeing a preview.

If you are a manager, the cost of a bad hire is astronomical: not only can the wrong person be bad at their job, a toxic person can poison an entire team dynamic. This is why a common piece of advice for hiring managers is to take the candidate out to lunch to observe how the potential hire treats the restaurant employees. No matter how polished the candidate is, if someone can’t muster basic respect for the person bringing their sandwich, what happens when they’re stressed at work, dealing with colleagues they don’t think they “need”?

Be the One Who Give the Tests

I’ve started noticing invisible tests everywhere. How someone returns their shopping cart when no one’s watching. Whether they remember small details you mentioned weeks ago. How they react when the wifi goes down during a video call. These moments tell you more than a dozen interviews ever could.

In the era of AI, this approach becomes even more critical. People with bad intentions or just lazy people can now write more persuasively, obfuscate their weaknesses, and come across as more skilled than they actually are. It’s getting harder to tell the bullshitters and fakers from people with actual skills and character.

The small, unguarded moments reveal what polished words cannot. The person who says ‘I’m detail-oriented’ isn’t nearly as informative as the one who actually noticed the brown M&Ms.

Stop waiting for people to tell you who they are.

Let invisible tests tell you instead.

If you’re into the intersection of AI, innovation, and actually doing the work—join my newsletter. I share stories, tools, and experiments from the front lines: camhouser.com/newsletter

Thanks to previous readers: Cansafis Foote, Rik Van Den Berge, Julie Kwok, Adam Siegel, Dominik Gmeiner,