LOS ANGELES — Raunchy comedy is having a rough run at the box office.

Moviegoers turned out in strong numbers over the weekend for the well-reviewed fifth chapter in Paramount’s “Mission: Impossible” series, which sold about $56 million in tickets. But it was an unexpected misfire that caught Hollywood’s attention: “Vacation” (Warner Bros.) became the fourth R-rated comedy of the summer to receive the cold shoulder from a wide audience.

There has been a lot of shock. Where is the awe?

“Vacation,” marketed with images of its stars smeared in feces, took in $14.9 million, for a total of $21.2 million since arriving on Wednesday, or about 35 percent less than most box-office analysts had expected. Warner Bros. and its New Line unit decided to release “Vacation” at the end of July because they had success in 2013 on a roughly similar date, when their R-rated “We’re the Millers” collected $37.9 million over its first five days.

“It’s lighter than what we had thought, no question about it, but younger audiences are responding,” said Jeff Goldstein, executive vice president of domestic distribution at Warner Bros. He noted that ticket sales increased from Thursday to Friday and again from Friday to Saturday. “That means word of mouth is great,” he said.