The good news: hotel bedding is getting washed more often. The bad: Not everywhere.

Those polyester floral bedspreads that once used to grace the beds at every major hotel chain in the United States are finally being phased out. Their busy patterns weren't just ugly—they also conveniently hid dirt and stains, allowing hotels to wash them infrequently. Recently, though, companies such as Marriott, Hilton, and Crowne Plaza have been replacing the old spreads with bright white duvets that have removable covers, which are presumably easier to launder. But even if travelers can be pretty sure they're getting newly washed duvet covers at luxury chains such as Ritz-Carlton and Four Seasons, the unfortunate truth is that most hotels still aren't cleaning their bedspreads or duvet covers between each guest.

Laundering frequency can vary wildly within the same hotel chain, says Bjorn Hanson, head of the leisure practice at PricewaterhouseCoopers. Starwood says its Sheraton and Westin duvet covers are "carefully inspected every day" by housekeeping for dirt and wrinkles and changed "as necessary." Hilton's housekeepers eyeball duvets daily, says spokeswoman Jeanne Datz Rice, and duvet covers at busier resorts, where guests are more likely to stain them with suntan oils, get washed "every few weeks." Wyndham says its staff scrutinizes bedding on a daily basis, but adds that each room undergoes a "deep cleaning [only] once per quarter." Crowne Plaza's duvet covers are laundered "as often as necessary," according to a spokeswoman. A more welcome stance for travelers concerned about the cleanliness of their bedding comes from Marriott, which is the only large-scale hotel company that now guarantees duvet covers are washed between guests—at least at its higher-end Marriott, J.W. Marriott, and Renaissance hotels.