Hotel booking sites can be useful tools when comparing prices, locations, and amenities, but some services use deceptive tactics to get you to click “book.”

A new report spotted by Travel + Leisure determined that those “one room left” alerts you sometimes see while perusing hotels can’t always be trusted. Led by the UK-based Competition and Markets Authority (CMA), the eight-month investigation concluded that many sites use “pressure selling” to create a false sense of urgency in hopes that customers will book a room more quickly than usual. Similar notices about how many people are looking at a particular room or how long a deal will last are some of the other tactics travel booking websites employed.

The CMA also found that some discount claims had either expired or weren’t relevant to the customer’s search criteria, and hidden fees—like the much-maligned "resort fees"—are sometimes tacked on at the end of the booking process. (To be fair, many hotels are also guilty of this practice.)

The report didn’t drop any company names, but the consumer agency said it warned the sites that legal action would be taken if their concerns weren't addressed. The companies could be breaking consumer protection law, the CMA notes.

“Booking sites can make it so much easier to choose your holiday, but only if people are able to trust them,” Andrea Coscelli, the CMA's chief executive, said in a statement. “Holidaymakers must feel sure they’re getting the deal they expected … It’s also important that no one feels pressured by misleading statements into making a booking.”

Still, booking sites remain a convenient option, so if you decide to use one, just take your time and be cognizant that some of the claims you're seeing may not be entirely truthful.

[h/t Travel + Leisure]