In massive warehouses across the country, returned merchandise is beginning to pile up with the advent of the holiday season. Some looks more used than new.

Curtis Greve has seen camcorders with tapes of weddings still inside, microwaves with food still in them, and once, even a 23-year-old Stanley Thermos that had been returned because the customer said it did not heat anymore.

Greve is president of the retail service business of Blawnox-based Genco Distribution Systems, the world's largest provider of what's known as reverse logistics -- a fancy way of saying it moves stuff from stores that can no longer sell the goods to outlets that think they can. And as the piles of used merchandise that he's observed prove, not everything returned is just like new.

For retailers that operate on thin profit margins, it no longer is an issue they can ignore. Many stores this year have begun cracking down on loose return policies that in the past may have allowed consumers to wear and return clothing, tape special events on borrowed video machines, and make popcorn in no cost microwaves.

Customers are being given less time to return items, and some stores are even denying returns to customers who do it too often. The goal is to earn back some of the money that that's lost in return fraud and shoplifting, even at the cost of losing customers who have grown as accustomed to returning merchandise as they have to buying it.

Guess, Staples, the Sports Authority and the Limited are among merchants that have started using software that helps retailers track a consumer's return history and decide whether or not to allow the return. While the chains declined comment, customers at Target and The Children's Place also reported problems returning purchases.

It's about time, say some experts.

"What retailers are up against are a lot of people who take advantage of their generosity," said Richard C. Hollinger, professor in the department of criminology, law and society at the University of Florida. "We're all paying for it right now."

Refund fraud has only recently been discovered, Hollinger said, although it has been around for a long time. Years ago, retailers allowed customers to bring anything back, sometimes even if the item was purchased somewhere else.

Hollinger tracks inventory shrinkage in his National Retail Security Survey and estimated that retailers lose $33.6 billion annually in merchandise that is stolen or lost. Almost half of this is due to employee theft and a third is from shoplifting. But many items that employees steal or customers shoplift, turns out, are returned for money or store credit or sold elsewhere.

"It was only when retailers started to go on eBay and realize that there were large quantities of their merchandise on sale" that they started to tighten their return policies, he said.

Hollinger, whose surveys show that the more expensive the merchandise, the more it is shoplifted, stolen, or returned, thinks the stricter policies will save retailers and consumers money.

Jim Fink, who works in a shoe department at a Downtown department store, said his department sees returns of 15 percent to 18 percent.

Sometimes, relatives try to return unworn shoes after someone dies -- even if it's been years since the purchase. Just as often, he said, people will try and return shoes that have been worn for years or people will buy and return a new pair of shoes every week.

It is not just the big retailers that lose on return fraud.

Sonya Haber, manager of Littles Shoes in Squirrel Hill, said a customer once tried to return shoes that had been eaten by a dog, passing the bite marks off as a manufacturing defect.

Sometimes, a customer will buy shoes and then leave them, receipt and all, in a restaurant by mistake, and someone else will find them and try to bring them in for a refund. Haber has also seen customers bring back shoes that were purchased 10 years ago and ask to exchange them.

"Some consumers abuse return policies," she said. "But the department stores created it -- they took everything back."

Littles allows for returns for up to two weeks after purchase if shoes are still in their original condition. But the store also has its own tracking system. Customers are asked for their phone number when they make a purchase. The date of purchase and item purchased is stored in a data base.

This optional system helps prevent return abuse, Haber said, and also helps customers keep track of their purchases and the likes, dislikes and shoe sizes of family members.

"Our customers seem to like it," she said.

But some fear that such return policies may isolate or scare consumers who want to keep their privacy.

The biggest problem with most software that traces returns is that it does not track why a customer brought it back, said Gayle Marco, associate professor of marketing at Robert Morris University.

Marco said the policies hurt consumers who buy things without trying them on first or bring clothes home to see if they match with another outfit. Some also fall prey to the thrill of the purchase.

Marco said that consumers are worried about being tracked, but "they're already tracking you," she said. "It's just another form."

This does not convince customers who are accustomed to the shop-and-return philosophy.

"The mirrors in there are skinny mirrors," joked Jill Jacobs of Jefferson Hills as she left the TJ Maxx at the Waterfront. "I'm the queen of returns."

Jacobs said that she sometimes likes to buy clothes and try them on with certain shoes at her house, or in a different light. She does not like the idea of her returns and purchases being tracked, and said being denied would cause her to start shopping at a certain store.

Jamie Michaels, of the North Hills, felt this way after a bad experience with The Limited, one of the stores that uses return tracking software. She bought a $265 suit and brought it back over a month later, still in its original garment bag, with the receipt.

The store offered her a fraction of the original price because too much time had passed.

"I threw a fit" and, after a lot of arguing , Michaels got her money back.

But she is frustrated because she is accustomed to rushing into the store, grabbing the size that fits her and trying it on at home. "I am hesitant about going back," she said. "They're just going to alienate people."

Michaels, who once returned boots a year after she purchased them, thinks that stores with less strict return policies will become more popular.

Words like these might cause retailers to think twice about putting limits on return policies. But business sense argues that stricter policies might lead to better business.

Retail has not been strong for a few years, said Robert Morris's Marco, and you can't blame the stores for wanting a stricter return policy.

"Retailers went to a loose return policy," she said, "and a lot of them got burnt."

Even the Privacy Rights Clearinghouse, a nonprofit consumer advocacy organization, said that the ability to return merchandise is a privilege, not a right. While the organization wants more transparency in return and tracking policies, communications director Jordana Beebe said that retailers have a right to try to minimize the impact of consumer fraud.

Genco alone processes over $6 billion in returns a year. With returns costing retailers, a stricter return policy may save money -- even if it creates a few malcontent shoppers.

Shopper Michaels used to work at Sears, which allowed many returns because of its slogan "Satisfaction Guaranteed or Your Money Back." At Sears, there is no specific time frame for returned items with a receipt, and while the receipt says that six months to a year is reasonable, it considers returns on a case by case basis.

"Our over-arching policy is satisfaction guaranteed or your money back," spokeswoman Lisa Gibbons said, adding: "We do hope that our customers are honest with us and we want to provide satisfaction."

Despite tighter return policies at many stores this year, Genco's Greve still expects a good amount of returns this year and, in a way, is banking on it since returns are good for his business. His clients include Sears and Best Buy, which only allows returns for up to 30 days.

"We're preparing for the wave of returns," he said. "Hopefully it will be a great Christmas and our stores will do really well."