Business travelers beware -- the next time you think about charging little extras to your expense account, consider worst-case scenarios.

One woman was immediately fired for putting a $9.95 hotel room movie rental on a business travel expense report, according to Peter Goldmann, president of fraud-prevention consulting firm FraudAware.

"Most companies wouldn't do that, but her manager's point was, 'if we allow it and it happens a thousand times a year, everyone is allowed to break the law,' " Goldmann said.

But based on the amount of expense account fraud he's seen, it's evident to Goldmann that business travelers know their way around the system.

Despite technological advances in expense reporting, companies are still having a hard time detecting fraud. On average, it takes a company 24 months to discover expense account fraud, according to a 2010 report by the Association of Certified Fraud Examiners. And this kind of fraud is more than four times as likely to occur within a business as corruption or financial statement fraud.

"The clever people are the ones that are committing the fraud," said Allan Bachman, education manager at the Association of Certified Fraud Examiners

"They are the ones who are getting the cab drivers to give them blank receipts, asking for double receipts at hotels and restaurants, masking one transaction as another, using cash to buy something and getting a blank receipt and putting in for more than the transaction it was. There are an endless number of possibilities here."

And whether or not companies are using an automated system or manually compiling expense reports with receipts, without constant oversight and accountability, there simply aren't enough "mousetraps" to catch the gamers, Goldmann said.

Besides benefiting from the inflated reimbursement check that comes in, many business travelers are padding their expense account charges because they feel like they deserve it, Bachman said.

"Employees are thinking, 'They make me travel on a Saturday night, they can afford to buy me a steak for dinner,' " he said.

If they have to travel on their own time for the company, employees are looking at quality over saving money and pampering themselves rather than succumbing to the dirges of business travel.

"People are giving themselves a treat by putting in a little bit more than they should have and getting a little more back than they should," said John Geron, a public accountant who audited expense accounts for 44 years.

Employers should be looking for general vagueness, a disconnect in the length of a trip and the charges associated with it and for odd items that often signal that an expense report has been falsified, Geron said.

Those items can include everything from an "accidental" use of the company credit card on a business trip to purchase a suit coat to listing every single can of soda or pack of chewing gum purchased.

"Someone is going to look at that and ask, 'Why are all these things reimbursable? Do you not chew gum when you're not traveling?' " Geron said.

These unexplained and seemingly nonbusiness related charges are what Pat Fragale, president of Directravel , a company that manages travel on behalf of corporations, calls "visual guilt" on an expense report.

"The trip was booked for 'x' and you're trying to process 'y,' " he said. "Something has to be explained."

Business travelers looking for a fat reimbursement check know that it's all about the receipts when it comes time to turn in an expense report. They either buy fake receipts online in whatever amounts they want or cajole blank ones out of their favorite restaurants, Bachman said.

Bachman heard of one instance where an employee frequented a certain restaurant franchise and asked for receipts so often, they gave him a pad of them. The employee would turn in fake receipts for lunches he never had. He was only caught -- and fired -- when he began turning them in for locations where the franchise didn't exist.

While it is possible for credit card companies to set up "triggers" and alerts on company cards or specific travel cards, automatic tracking still requires a great deal of oversight, Bachman said. Some companies have instated zero tolerance policies for expense account fraud; the possibility of termination helps keep employees honest.

There is still much debate over whether automated processing of expense reports curtails this kind of fraud.

Fragale believes that automated reporting systems are cutting down on expense account fraud, and the breakdown occurs in the manual process where numbers can be changed and receipts multiplied. His company offers a checks and balances system to corporations, ensuring that fraudulent activity doesn't happen.

But most companies don't use automated systems, he says.

Paper reporting often gets shuffled to the bottom of the priority pile.

"The volume of paper is too much for any one manager to thoroughly handle," Goldmann said. "The employees know that and they take advantage of the fact that their manager is not going to be thoroughly reviewing it and signing off on their expenses. It's easy oftentimes to include phony receipts, because business managers just aren't paying attention."

Goldmann also said that automated systems can't distinguish between legitimate and false receipts.

So just what are employees getting away with on their expense accounts? Upgrading hotel rooms, excessive taxi rides, double-billing for plane tickets, seats and baggage fees, luxury rental cars, fake lunches and dinners, layovers for personal visits and heaps of laundry on overnight trips, according to Goldmann, Geron and Bachman.

Whether these false charges amount to a bit of personal pampering or thousands of dollars of additional income, expense account fraud is a crime. It's just a matter of getting caught. Depending on company policy, fraudsters may be subject to immediate termination if the company finds out, Bachman said.

Goldmann knows of a sales manager who lost her job when she abused the gift limit on her expense account. While 75% of the purchases were for actual clients, she also used the card to purchase expensive gifts under family names. Then, she sold those gifts on eBay and reimbursed herself.

It proves that while oversight and tight policy can rein in expense account abuse, employees are also getting creative.