Dear Tripped Up,

During a trip to Europe last summer, my husband and I woke up in the Abbaye des Vaux-de-Cernay, a hotel about an hour’s drive southwest of Paris, covered in what we are sure were bedbug bites. Our daughter, who was in a separate room, was fine. After checkout, we got in touch via text message with our dermatologist, who confirmed from our photos that they were most likely bedbug bites and suggested medications. We discarded and replaced our pajamas and some other clothes, had the rest dry-cleaned, and saw a doctor to get prescriptions. We also called and emailed the hotel to inform them and request they reimburse both our expenses — about $800 in all — and our stay, which cost about $1,050. But management responded slowly and ultimately refused, forwarding a report from a pest-control company saying that no bedbugs had been found in our room. The report was dated a week after our stay, presumably after the room was cleaned and the linens changed. We believe the hotel owes us $1,850. Can you help? Stacy, Farmington, Conn.

Dear Stacy,

I’m imagining readers — especially those in a hotel room — squirming at your story. No one likes the idea of bloodsucking bedfellows, and if bedbugs were the culprit, it seems as if you should be compensated for some, if not all, of your costs.

But proving a bedbug attack can be challenging if the hotel disputes your account, and Julien Davain, the deputy general manager of the property, put up a spirited defense. He told me in a phone interview that the hotel cleaned your room after you checked out, but only because it did not receive your first email until late that night. At that point, he said, the room was closed off and the hotel hired a top pest-control company from Paris, As de Pic. As soon as scheduling allowed, he said, the company sent a trained detection dog, turned the room upside down and found no sign of bedbugs.

Some hotel managers might have adopted a customer-is-always-right stance and reimbursed your expenses anyway, but not Mr. Davain. “If I reimburse Madame, it is like I am guilty,” he said. “We really wanted to do a gesture, but if we do so, that’s it. We open the door to say we are guilty.”

He suggested that you might have been bitten by other insects or spiders on the hotel grounds, which include forested areas and a lake. Mr. Davain pointed out that his son, who goes to a nearby school with a lot of outdoor programs, often comes home with unexplained bites.

You disagree, of course, and your insistence that these bites came from bedbugs at the hotel seems logical. You point out that bedbug bites often come in straight lines, which I confirmed with Ed Rajotte, an emeritus professor of entomology at Penn State University.

I later emailed him your photos and shared Mr. Davain’s theory that other critters had been involved. “The pictures are consistent with bite patterns that bedbugs would cause,” he wrote back. “The alternatives seem unlikely.”

But my best efforts to press Mr. Davain went nowhere. It also doesn’t help that bedbug bites sometimes don’t show up for days or even weeks after one is bitten, according to the Centers for Disease Control and Prevention, widening the possibilities of where exactly the creepy encounter took place.

I discussed your complaint and shared your photos with Jeffrey Lipman, a lawyer in Iowa who specializes in class-action bedbug cases. He and a physician-entomologist he works with also concluded your bites were “consistent” with the work of bedbugs.

But you would most likely need photographs of the creatures on site to prove it, he said.

And not just any photos will do.

Another traveler, Karen from Voorburg, the Netherlands, wrote to me after a stay last Halloween at the Empire Hotel in New York City. Because of a past encounter with bedbugs, she said, she routinely examines mattresses when she checks into a hotel.

After she found and shot photos and video of what she believes were bedbugs in her room, staff members moved her to another room, where she found more. She then stayed in a third room and was not bitten, but told me that front desk staff “looked embarrassed” and promised her a refund. Months later, she has not received one. (“We do not acknowledge any bedbug presence in that room on that date,” Ecker Cano, a manager at the Empire, wrote in an email to me. He added that the hotel followed industry-standard protocols to prevent infestations.)

I sent Karen’s photos and videos to Mr. Lipman, but they just weren’t clear enough. “It’s consistent with a bedbug,” he said in a phone call. “But to be sure, you’ve got to have a lot better photographic evidence.”

The appearance of a few bedbugs is not a hotel’s fault, he said, noting that “every hotel” gets bedbugs. (A 2017 study by the pest-control company Orkin placed the figure at more like 80 percent.) A well-designed and well-executed prevention effort is what makes the difference. “If they’re following appropriate inspection protocols, they should be able to find the bedbugs before they ever bite a guest,” Mr. Lipman said. Some hotels, he said, offer rewards to staff members who find bedbugs.

The housekeeping team at the Abbaye is “trained to be vigilant for any signs of bedbugs during routine cleaning,” Mr. Davain wrote in a follow-up email. If there are any suspicions from staff or guests, the hotel holds off on renting the room and calls in the inspection company. That has happened three times in two years, he said, and all three inspections found the rooms to be bedbug-free.

Alas, I couldn’t get your expenses covered, Stacy, but perhaps I can help you and other readers avoid such situations in the future.

Before booking a property, check the reviews for mentions of bedbugs. (Google and Tripadvisor reviews are searchable by keyword.) One or two complaints over the years are not an immediate cause for alarm, although “No results found” is certainly better.

When you arrive, even jet-lagged, resist the urge to collapse right into bed. First, put your luggage in the bathtub, recommended Dr. Rajotte of Penn State. Next, pull back the bedding, and check for bedbugs on the mattress — especially under the “welting,” or fabric-covered cords, around the edges. Then check behind the headboard, on nearby furniture and even behind any art hung above the bed, he added. Also be on the lookout for the tiny shells left by nymphs when they shed their exoskeletons, and spots that might be fecal matter.

If you see anything, document it as best you can, in as much light as you can, and as sharply focused as your phone allows. Then share your findings with the hotel staff right away.

But bedbugs are wily and flat enough (when not engorged with blood) that you may miss them. If you wake up with bites, inspect everything again and photograph what you find before fleeing the scene.

Some online sources suggest capturing a suspicious insect and taking it with you as evidence. But why knowingly bring a bedbug into your space? A photo can’t cause an infestation.

When you get home, experts recommend unpacking in the bathtub, vacuuming out your suitcase and running all your clothes in a hot dryer for at least 20 minutes to kill any bugs and eggs. Unfortunately, bedbugs love to travel too.

If you need advice about a best-laid travel plan that went awry, send an email to TrippedUp@nytimes.com.

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