Most sales aren’t really sales. There are six common ways a discount misleads you, and each one has a check that takes about ten seconds.

I spent 30 years in marketing, and I’ve built most of what’s on this page. By the end, you’ll be able to look at a sale sign and know, before you buy, whether the discount is real.

1. “Up to”

“Save up to 50%.” Your eyes land on the 50. “Up to” is two small words in front of it, and most of us skip right past them.

That 50% is the best case, often for one item in the back corner of the store. The thing you actually want is more likely 10% off.

The Federal Trade Commission tested exactly this. Researchers showed people an ad for replacement windows that promised energy savings of “up to 47%.” About 43% of the people who saw it came away believing a typical customer would save about 47%. Adding a line that said the average savings was 25% barely changed that. The FTC’s takeaway: when an ad says “up to,” a lot of people hear the top number as a promise. The agency’s position since then has been that an “up to” number should be one that all or almost all customers can actually get.

The check: when you see “up to,” say the sentence out loud with the smaller number. “Some items are 10% off.” That’s the real sign.

2. The permanent sale

This is the price tag with a big number crossed out and a smaller number beside it. The trick is that the crossed-out number was never really the price. Nobody paid it. It exists so the real price looks like a bargain.

This one has been in court. In December 2016, the Los Angeles City Attorney sued four of the biggest department store chains in the country (J.C. Penney, Kohl’s, Macy’s and Sears) over this exact practice. One example in the complaint was a necklace advertised at 75% off an “original” price of $120. According to the city, it went on sale online at $30 and never sold for more than $30. Those are the city’s allegations, not findings by a court.

To be fair, an old price can be real. If the store actually sold the item at the higher price last month, the discount is honest. The tell is a crossed-out number with no date on it, attached to a sale that never seems to end.

The check: if the sale has been running every time you’ve visited the store or the site, the sale price is the price. Decide as if the crossed-out number isn’t there.

3. The countdown that resets

You’re on a checkout page, and a clock says the offer ends in 9 minutes and 40 seconds. Your heart rate ticks up a little, and you click Buy.

Reload the page first. On a lot of sites, the clock starts over. There was no deadline. The deadline was you.

Regulators have named this one. The FTC’s 2022 staff report on manipulative web design, Bringing Dark Patterns to Light, lists countdown timers and fake scarcity claims among the design tricks used to pressure people into buying.

The check: reload. If the clock resets, you have all the time in the world. Come back and buy when you’re ready.

4. The coupon you had to earn

“Give us your email for 10% off.” “Install the app for 15% off.” “Share with a friend for 20% off.”

Call it what it is: a purchase. You pay with your inbox, your phone’s storage, or your friend’s inbox, and in my experience the 10% is often already built into the price.

I’ve built these offers. The math on the back end is simple: the email address is worth more to the company than the 10%, or the offer wouldn’t exist.

The check: log out and look at the price in a private browser window. If it’s the same, the coupon was the only thing being sold.

5. “Members save more”

The loyalty card, the free membership, the rewards program. It’s the same trick as number four, played over a longer game.

The discount is real. What it costs is a record of everything you buy, plus a steady stream of reasons to come back. Over a year, that record is worth more to the store than the discount is worth to you.

This one is fine when you’d shop there anyway. If you’re already in that store every week, take the card. Just know what you’re trading for it.

The check: at the sign-up screen, ask one question. Would I have come here, or bought this, without the card?

6. The stack that isn’t

“Extra 20% off clearance.” “Buy one, get one free.” Doorbusters on top of the sale on top of the coupon. The layers feel like they add up to a steal. They add up to whatever the store decided you’d pay before it printed the first sign.

Buy one, get one is the clearest version. In the same Los Angeles case, the city alleged that one retailer advertised buy-one-get-one-free on products that were never sold as a single item at the listed price. There was no “one” to buy. There was a two-pack with a marketing name on it.

The check: start from the receipt, not the sign. What did I pay, for how many, all in?

One tool for all six

On Think Sharper, any claim gets three questions before we trust it. For a discount, they go like this:

• Stake. Who set this number, and what do they get if I believe it? A sale sign is written by the person who wants the sale.
• Source. What is the discount measured against? A real price from last month, or a number nobody ever paid?
• Steelman. What’s the honest reason this might be a real deal? Sometimes there is one. Clearance is real. End-of-season markdowns are real. If you can’t find the honest reason in ten seconds, there probably isn’t one.

And before all three, one move: say the real price out loud. Skip the percentage and say the number you’ll actually pay today, all in.