Buy one, get one free! Spend more to get free shipping! Save 10% with this special discount code! They're the kind of sales pitches consumers often find impossible to resist. Yet spending money to save it — or "spaving," as the practice has come to be called, rarely benefits the consumer. Instead, retailers' clever marketing ploys convince consumers they're getting a deal, when often they're just overspending. 

In short, buyer beware, experts warn.

"I understand the appeal of getting to checkout and a notification pops up saying spend $10 more to get some perk," LendingTree senior economist Jacob Channel told CBS MoneyWatch. "But 90% of the time, when you break it down, it doesn't make sense. You're not actually saving money if you are spending more of it."

Deal or no deal?

A number of common marketing offers dangle the lure of savings — provided that you splash enough cash. They include:

• Spending above a certain amount to get a "free" gift
• Spending enough to qualify for free shipping
• Buy one, get one
• Buying extra items to use a coupon or discount code
• Subscribing to a service to qualify for a discount

If these tactics sound familiar, it's because they're widely used by a range of retailers, from grocery chains to clothing stores, noted Bankrate personal finance expert Ted Rossman. 

To be sure, there's nothing illegal or even especially underhanded about such offers — merchants are in the business of making money, after all, while consumers bear some responsibility for determining if a deal is worthwhile.

By the same token, it's also on shoppers to be alert to sales gimmicks that subtly nudge them to overspend.

"Retailers have always known this trick, and they're really good at what they do," personal finance expert Rachel Cruze told CBS MoneyWatch. "They know that if we put a sale on or offer free shipping if you spend 'X' amount, you'll spend more money. Psychologically, they're good at knowing how to entice people."

Why shoppers fall for it

But why do consumers fall into the trap of spending more in the name of saving? Part of it often comes to FOMO, or the fear of missing out, on a limited-time sale or other purported bargain, money coach Nicole Victoria told CBS MoneyWatch.

"It's about loss-aversion, or the perception of loss," she told CBS MoneyWatch. "You feel like you're losing money by paying for shipping, and you've invested time and resources into filling up your shopping cart, so you'd rather gain something more." 

Of course, spaving isn't always a mistake. Sometimes spending more money on something you were already planning to buy makes good financial sense and can yield actual savings. But Victoria said it can get downright wasteful when, for instance, you purchase large quantities of perishable goods you can't possibly consume before they expire or go bad. 

"It's not all bad, but the part that's more harmful is the impulse buy and lower-quality items, the fast-fashion example or stuff you don't necessarily need. Buying in bulk isn't great if you're going to throw out the leftovers," Rossman said.

These days, meanwhile, spaving can pile on credit card debt at a time when APRs hover near record highs, he added.

How to avoid spaving

In general, it's wise to disregard deals that invite you to spend more money than you'd planned, experts said. 

"Sometimes, you're better off ignoring notifications and only buying what you were originally going to buy. It's a matter of not being distracted by a shiny thing," LendingTree's Channel said. 

It's also helpful to keep in mind that the merchants behind "buy one, get one" and similar deals have a mission — get you to spend as much as possible in order to grow their revenue. 

"Keep that mentality in mind going in. They're not out there trying to help you save money," Channel said. 

Other tips for resisting the temptation to add goods to your shopping cart in hopes of saving money or earning a reward:

• Stick to your list. List what you need when shopping — and stick to it.
• Unlink your credit card from retail websites. Storing payment information online makes it easy to spend money with just a couple clicks. Sure, it might seem like a hassle to enter your card number and go through the checkout process, but this is just the type friction that can help curb your spending. 
• Unsubscribe from promotional emails. Sales notifications alert you to events and direct you to shop on sites that you hadn't planned on visiting. And beware of social media — if you follow accounts on TikTok or Instagram that encourage you to shop (often because they have a financial incentive), that can lead to more impulse purchases. 
• Sleep on it. Institute a 24-hour rule before making any unplanned purchases. 

Megan Cerullo

Megan Cerullo is a New York-based reporter for CBS MoneyWatch covering small business, workplace, health care, consumer spending and personal finance topics. She regularly appears on CBS News 24/7 to discuss her reporting.