You see a cool YouTube video of people running on water. It's called "liquid mountaineering," and you share it on Facebook and Twitter. Then you find out it was a viral marketing campaign. And you feel like a tool.

A YouTube video depicting "liquid mountaineering"—supposedly a new extreme sport featuring rugged Europeans running on the surface of water—bounced around the blog and became a human interest segment on a local news show—despite being a viral hoax and advertisement for water-resistant shoemaker Hi-Tec.

Viral marketing campaigns are insidious. Though theoretically harmless—you only wasted a minute on liquid mountaineering—being fooled by them makes you feel like a buffoon. For the joy of a viral video stems from the feeling of discovery—that you have discovered a regular person who, in the comfort of his or her natural setting, did something novel, and you—and everyone you sent it to—connected to it.

But if the video is actually the product of focus groups and marketing executives, the joy of discovery vanishes—or is at least no more joyous than finding the perfect pair of "broken in" jeans at Abercrombie. You just wasted precious time and energy promoting a product. And it may have been made by a company that you don't even like! Forwarding a viral marketing campaign means possibly losing all your internet cred.

But as marketers get more sophisticated with their infectious viruses, and regular people can more aggressive about extolling the virtues of their favorite videos, photos and songs, the line gets blurred. Four signs that the cool viral video you just found is actually a viral marketing campaign:

1. Product Placement and Logos
 The biggest sign that your cool viral video is actually a marketing ploy is, of course, the marketing part. Watch for close-ups of logos or people talking about how a particular product provided a "breakthrough," as the liquid mountaineers do, demonstrating how water beads and falls off their shoes.

Even in user-generated material rhapsodies like unboxing and haul videos, regular people don't treat purchases as revelatory. Their videos are about themselves and their actions, not the objects that enable them. Exceptions: Americans agape at zany Japanese stuff, tacky people flashing status logos, dogs humping surprising appliances.

2. The People are Beautiful and Their Clothes Are New
 Real people have acne and frizzy hair. Their clothes don't match, their muffin tops show, their jeans sag at the butt. Though some viral videos use "real people," real videos do not use actors. If the lovably exuberant cast of the video you're watching look suspiciously like actors, they probably are. Especially if each one sports a slightly different pan-European accent, as the liquid mountaineers do. Exception: Obama Girl jiggling her boobs for democracy.

3. Companion Website with Flash Animation or Elegant Fonts Sometimes, viral video makers point you to their personal websites and blogs. Sometimes, these are very sophisticated. You can't prove a video is a plant just because its maker has a flair for graphic design, but the inverse is true: If the viral video uses a cheesy font like Comic Sans or a Windows default like Arial (real designers use Helvetica) it's probably not a marketing campaign. The viral marketer's slick site will eventually point you to their product, and will have been designed by professionals, who are physically incapable of using a font like Curlz MT.

4. It's Too Perfect
 The production value is too good; the lighting is too buttery; the music and edits are too smooth; the details are too impeccable. Viral campaigns never have microphone feedback, and if the camera shakes, it's the skillful Blair Witch shake of a high-quality camera, not the thudding cheeseburger brawl shake of a cellphone camera. For us, the detail that sealed the deal on liquid mountaineering was this cut to a Jesus doll dangling from the rear view mirror.

If it had been a rosary, fine. Ditto drug paraphernalia, fuzzy dice, or a lei. But an ironic cartoon Jesus sold at Urban Outfitters? It's too perfect for a video entitled "Walk on Water," too closely fits a middle-aged marketer's briefing book on How to Sell Shit to Young People. Of course, once Saatchi & Saatchi adds this blog post to their handbook, nobody will make that mistake again, and marketers' ragged-breathed chase of virality and tech-savvy trendsetters will begin anew.