When trying to sell a home, the number one rule is to declutter and make the place as clean and open as possible. (See the house staging tips on this list.) For a while, retail stores have followed the same concept, utilizing super-wide aisles, minimalist design (relatively speaking), and smaller shelves, with fewer items on those shelves. Shoppers said they loved the lean, more streamlined retail experience. So why is clutter back in a big way at stores all over the country?

Why? Because apparently when stuff is piled up and thrown all over stores, shoppers tend to buy more stuff.

The most obvious case in point is Walmart, which suffered a much-publicized identity crisis over the past few years. While trying to appeal to more affluent shoppers during the recession era, Walmart trimmed the number of items in its stores by nearly 10%, and pushed both prices and design upscale in the direction of Target and Whole Foods. The moves proved to be disastrous for sales.

That’s why, as the NY Times now reports, Walmart is leading a pack of retailers that are restocking their shelves and cramming in as much merchandise into, within, and between aisles as possible. Call it strategic clutter. Or mess by design.

The reason these retailers are untidying up is because the overloaded appearance gives off distinctly strong impressions to shoppers. Some may think “nasty.” Yet, for others (many, many others), a messy, random pile of goods connotes “bargain.” A source quoted in the Times offers some insight:

“Historically, the more a store is packed, the more people think of it as value — just as when you walk into a store and there are fewer things on the floor, you tend to think they’re expensive,” said Paco Underhill, founder and chief executive of Envirosell, who studies shopper behavior.

Underhill is the author of Why We Buy, which reveals in eye-opening, sometimes disturbing fashion what’s going on in the minds of shoppers who are drifting mindlessly through the retail experience.

What’s interesting here is that, whether shoppers are aware or not, they’re making pretty big assumptions based on a store’s appearance. And we all know assumptions can prove costly for consumers. In this instance, the assumption is that if goods are thrown here and there or piled up semi-randomly in a store, the prices must be cheap. The customer gets the impression that the store isn’t spending money to tidy its appearance or streamline design, so presumably the customer isn’t paying for those things either. On the other hand, when entering a store where the options are few, and everything is neat and meticulously organized, the shopper gets the idea that the stuff sold there just has to be high-end merchandise. Why would the store put so much work and effort into display and design otherwise?

Dollar General is another pro-clutter retailer. The chain is standardizing the tops of its shelves at 78 inches (up from 62 inches in some locations) in order to provide more space to pile on the goods. The chain is also adding what it calls “speed bumps,” which, like the real thing, are meant to slow traffic down. Dollar General slows shoppers down with merchandise placed prominently near the entrance or sometimes in the middle of an aisle.

Retailers are constantly trying to catch shoppers’ eyes—to make them pause and consider a completely unplanned purchase. These speed bumps get in your way physically, attempting to prevent the quick, impulse-free-shopping escape.

The speed bumps add to the overall overloaded, messy appearance—an appearance retailers are striving for, mind you. Another interesting quote from the Times:

“Messiness, or pallets in the middle of an aisle, are also a cue for value,” said Ben DiSanti, senior vice president of planning and perspectives for TPN, a retail marketing consultant. “There are a lot of cues that the shopper picks up on in stores.”

None of these ideas are new, of course. Thrift stores, flea markets, and bazaars the world over have been offering customers a cluttered, messy, overwhelming, treasure-hunt-like shopping experience for quite some time. Now, however, it’s huge retailers copying the presentation and “design” of shabby secondhand stores. Whatever keeps ’em shopping, right?

Workers at these freshly cluttered stores now have a pretty good excuse for being lazy and not bothering to clean up: It’s good for business.