Christopher Elliott

Special to USA TODAY

When Mike Gnitecki left a so-so review online for the Omni Shoreham Hotel in Washington, D.C., he expected his comments to stick. But they didn't.

Less than two years after he penned a two-star rating for the property, TripAdvisor emailed him to say it had deleted his critique.

"We would like to let you know that Omni Shoreham Hotel has recently gone through a major renovation," a representative wrote in an email Gnitecki shared. "As a result, all reviews and photos posted before the change, including yours, have been removed in accordance to our policy."

Gnitecki, a paramedic in Longview, Texas, is one of a growing number of travelers who suspect companies that host user-generated reviews are censoring some comments. They might be right. Companies like TripAdvisor remove reviews for a variety of reasons, which users might consider censorship. It's something to consider as you review the reviews before your summer vacation.

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Can a site remove a review?

Gnitecki is troubled by his deleted review. But a quick online search revealed that TripAdvisor allows hotels to hit "reset" on their reviews after showing proof of a renovation. For vacation rentals, the site even requires that contributors write about experiences "that occurred within the current calendar year or up to two calendar years prior."

He's bothered because he didn't review any of the hotel's amenities, but the service he received at the Omni.

"The staff wasn't very helpful," he says. "I didn't care for the service."

What's more, he says TripAdvisor didn't offer a way for him to object to the removal of his review, "so I just let it go."

Sometimes, sites inform the reviewer of the deletion, but sometimes they quietly remove the write-up with no notification. And they can do it any time and for any reason.

Matt Kiefer, who runs a hostel website in Barcelona, Spain, remembers leaving a review for a restaurant in Barcelona on TripAdvisor. But shortly after the write-up appeared, the restaurant owner contacted him and threatened to sue him unless he deleted his comments, he says. He refused.

"Two days later, TripAdvisor deleted my review with no explanation whatsoever," he recalls.

He understands why a website is quick to push the "delete" button.

"A site that hosts reviews is there to promote the businesses and not to harm them," he says. "After all, they want these partners to pay to promote them or that the users can book the accommodation."

TripAdvisor didn't respond to questions about Kiefer and Gnitecki's deleted comments, citing "privacy" reasons.

"We believe in a travelers’ right to write online reviews and share their candid travel experiences with millions of other travelers," said Kevin Carter, a TripAdvisor spokesman. "TripAdvisor has been and continues to be a place where travelers can share the good, the bad and the ugly about their hotel stays, dining experiences and more."

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Sometimes reviews aren't even published

Consider what happened to Jerry Tilley, who made a reservation for a hotel in Zurich last year and then left an unflattering review on Booking.com. "The place was dirty and unpleasant," says Tilley, who works in the shipping industry in Oslo, Norway. But he says Booking.com declined to publish the review because he had used the word "asylum seekers" to describe his fellow guests.

"Those words can be understood as discrimination," a Booking.com representative said in an email Tilley shared. "We know that is not your intention, but people could understand this way and we would like to avoid any misunderstanding for all parts."

Booking.com didn't respond to questions about Tilley's case, but says that while its reviews are genuine because they're sent to guests after checkout, it reserves the right to remove any write-up if they're "deemed irrelevant or offensive."

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Who do you believe?

There's no such thing as free speech online.

Rating sites and online agencies can remove or refuse to publish a review for many reasons. What's more, the process is often opaque – which is to say, the site may or may not notify you and explain why it pushed the "delete" button.

The problem isn't that this practice occurs. These are, after all, businesses that have the right to publish whatever they want.

Instead, it's that they often present themselves as trusted resources that will help you "know better." But if reviews are indiscriminately deleted, are travelers getting the full picture? Maybe, maybe not.

Perhaps the biggest takeaway is this: Now more than ever, you can't believe everything you read. You may not be getting the full picture.

Why travel sites delete reviews

It violates their review policy. Every major review site has a review policy. For example, it may require that a review be noncommercial, relevant and unbiased. Break any of those rules and your review could be history.

You didn't stay at the property. Some sites require that you show proof of your stay. If you can't show that you were a guest, your review may disappear.

You wrote something offensive. Avoid abusive language, swearing, discriminatory remarks, threats of violence and political or religious commentary. Also, don't promote illegal activities. Some sites also don't allow you to post a phone number or email addresses to avoid doxxing.