Many years ago, there was an advertising campaign for a perfume called Cachet. It made quite a promise: “It smells different on every woman.”

The company sold boatloads of it, because who wouldn’t want something that was totally her own? The campaign was brilliant, but it was also sneaky.

Cachet did smell different on every woman. But because of each person’s distinctive body chemistry, every perfume does. Cachet wasn’t unique, and even though the campaign gave that impression, the company never actually said it was. The claim was accurate. It just didn’t tell the rest of the story.

Of course, this particular perfume is just one example in a wide range of similar stories, and yes, they happen in the auto industry as well.

Take winter gas. Virtually all gas stations are selling it, but you’ll usually find one or two that put out a big sign advertising it. You’ll note that the sign will just say, “Winter gas.” It’s up to you to think there’s something special about it and that you need it for the cold weather.

In reality, the only thing that’s special about winter gas is that it isn’t summer gas. Smog-forming vapors can escape into the atmosphere when you’re filling up, or if your gas cap isn’t tight. Gas companies refine the fuel for lower volatility, so it’s less likely to evaporate and pollute, but it’s an expensive process. It’s required by law in summer, when hot temperatures speed up evaporation. Colder temperatures naturally reduce evaporation, so the mandate doesn’t require this extra refining step in winter.

Stations could sell summer gas all year round, but it’s cheaper to make winter gas, and easier to meet the higher volumes sold in winter. Nothing special—but the sign might make you think otherwise.

And that “nitrogen-enriched” gasoline one company sells? Sounds like it does something special for your engine, but you’ll notice you’re never told exactly what that is. The nitrogen is simply an emulsifier. Gasoline contains additives, and someone discovered that adding nitrogen keeps everything nicely mixed together. Now, marketing execs wouldn’t think that writing “nitrogen-enriched” on big signs outside the station would make people believe that gas with nitrogen is better than gas without nitrogen…would they?

Even the car companies don’t always mention everything. Several years ago, one automaker crowed that its all-new model earned the top crash-test rating of “Good” from the Insurance Institute for Highway Safety in both frontal offset and side crash-worthiness tests.

So I shuffled off to the Institute’s website to check. The vehicle had indeed earned those glowing results. What the company hadn’t bothered to mention was that it also earned a “Marginal” rating for rear crash protection. Perhaps including that extra little nugget might not have made everything sound so impressive?

The moral of the story? The companies (at least most) won’t lie to you outright—yeah, I know, but bear with me—but they’re not above telling you just enough, and letting you come up with your own conclusions. When it comes to advertising, never be afraid to let your inner cynic rule.