Uber "vomit fraud" isn't new — the scam has been around for years — but rash of recent incidents in Miami have raised the alarm on social media.

Here's how the con works:

— An Uber driver drops off a passenger.

— The driver then stages a mess around the passenger's seat and takes photographs.

— The driver notifies the company that the passenger had an incident in the vehicle that required cleanup after the ride, such as spilled food or drink, or vomit, urine or other body fluids — and includes the photographs as proof.

— Uber thens sends a message to the rider, informing them that an adjustment has been made to the bill to reflect a cleanup fee that can range from $80 to $150, depending on the kind of fluid and quantity involved.

— The confused passenger tries to contact the company to dispute the additional charges. This can only be done through a "help" button on the app or through Uber's website.

— Uber then will usually respond with message to the effect that "the driver notified us that a mess requiring cleanup was left during your trip, which is why you were charged an additional $150." The photos that the driver took accompany the message.

According to the Miami Herald, even if you prevail in fighting a vomit charge, it still takes three or four emails back and forth with the company — enough to dissuade some people from bothering with the hassle.

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The Herald reported four cases in which Uber customers said they had been victims of vomit fraud, including one who said he was scammed by two separate drivers on the same night.

Another, who asked to remain anonymous, told the Herald she knows other drivers in South Florida have done it and won the disputes with passengers.

"They've been doing it for a long time," she said. "Many people don't review their emails or credit card statements, so the drivers wind up pocketing the $80 or $150."

Uber told the Herald that the vast majority of cleanup fee reports are legitimate and says it investigates any claims it suspects are fraudulent. Police are often reluctant to get involved in what they consider to be a customer service matter best left to the company, passenger and driver to sort out, rather than a crime.

One Twitter user offered some advice for Uber customers worried about being taken for a ride: Snap pictures of the vehicle's interior when you get into the car and right before you exit.