A growing number of smokers are trying to pull a fast one on hotels with a sketchy defense, according to hotel industry lawyer Stephen Barth. And he’s giving hotels advice on how to fight back.

The premise is that a tough-to-dispute policy will ensure that few people attempt to smoke in their hotel room.

First, some background: Today, it’s easy for non-smoking travelers to find a hotel that bans smoking on its premises. In fact, it’s the norm. The no-smoking trend kicked off in a big way in 2005, when Starwood’s Westin became the first large chain to announce a no-smoking policy trend in 77 hotels in its rooms, bars, public areas and restaurants, according to this USA TODAY piece written at the time. Other chains including Marriott and Hilton ultimately followed.

Here’s how some smokers may be trying to smoke in their rooms and cover it up to avoid paying their hotel a penalty charge, according to Barth, who operates hospitalitylawyer.com.

U.S. hotels that ban smoking on premises today charge the credit cards of guests suspected of violating no-smoking policies a fee of as much as $250. In a review of cases where the consumer successfully disputed the charges with their credit card company and gotten the charge reversed, he found a common thread: Most of those people had argued that they’d brought in the used cigarettes that housekeeping had found in their hotel-room trash can from their vehicle parked at the hotel.

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Whether that’s true or not is up for dispute, but it’s becoming a common-enough defense for Barth to warn hoteliers to take steps to combat that argument.

Among his tips: Hotels require a guest who’s checking in to sign a document – or a new clause on an existing check-in document – that makes clear that smoking cigarettes in a room and disposing used cigarettes in the hotel room trash can is banned and can result in an additional charge. Hotels, he said, should also make a point of gathering evidence from “several” eye witnesses.

Hotels face high stakes to get this right. All you need to do is a quick search TripAdvisor for comments about non-smoking rooms that smell like smoke, and you’ll get the picture if you don’t already.

In an ideal world from the viewpoint of a non-smoker, veteran meeting planner Joan Eisenstodt says that hotels would have someone who checks rooms as people check out. But she’s been around the industry for years and knows that the idea”will never fly” because it would add to labor costs.

“But then, if someone is there more than one night, housekeepers and mini-bar refillers could check – they go into the rooms and can do a sniff and trash test. As someone who is so sensitive to chemical and other scents, I’m covered under the (Americans with Disabilities Act.)…It may take a lawsuit to get them to pay attention.”

Road warrior Tom Siko agrees hotels need to get this right, from his point of view as someone who used to smoke, but first they need to figure out their business goal.

“Hotels really understand what they are trying to accomplish here. Are they looking for a casual revenue stream to boost their bottom line revenue or are they looking to really prevent damage to the hotel room? I would suggest that most properties are looking to do the latter. I don’t think that you can legitimately charge someone’s credit card for finding a cigarette butt in the trash can. That said, if housekeeping were to notice an aroma of smoke in the room or see damage caused from smoking (i.e. burns, stains etc), that’s a prime case to charge a guest for the damage,” Siko told me via email.

Siko said he’d always avoid smoking rooms when he did smoke – and then he’d go outside with a cigarette to the designated smoking areas for his fix.

“Smoking rooms always end up smelling and looking horrible,” Siko told me. “I have in the past notified the front desk upon check in if I smelled cigarette smoke and asked for another room. I fully support hotels charging customers who do damage to the property including the small of cigarette smoke on the walls and fabrics.”

Readers: This issue isn’t an easy one to sort out (and I’m not even bringing up the e-cigarette issue – yet). Please weigh in with your take!