Big Brother is about to start its 17th season in the U.S. Over those many years the show has had its share of controversial house guests, and host Julie Chen has been witness to them all. During a Hollywood Reporter roundtable published online Monday, Chen revealed the houseguest she found most difficult to watch.

As will come as no surprise to Big Brother fans, Aaryn Gries was the standout for Chen. Gries was known for her offensive remarks on the season that was clouded by the racism, sexism, and homophobia of several contestants. The comments in the house made national headlines at the time. The winner of Big Brother 15, Andy Herren, was openly gay.

Chen now says Gries’ transformation came as a surprise to the Big Brother producers, who had her pegged as an all-American favorite.

“The thing that was hardest for me to watch was overt racism in the house [in 2013]. This girl, Aaryn, when she was first cast, we thought was going to be America’s sweetheart, the gorgeous blonde from Texas. She knew how to give those beauty-queen answers in her interviews. But after a few weeks, that beauty faded and the inside came out, and the inside was ugly to the bone. She said homophobic and racist things. She made fun of women at the local nail salon. (In a stereotypical Asian accent) ‘Oh, you pick color, you pick color.’ And that was the least offensive thing she said.”

The sequestered Big Brother 15 cast and jury were made aware of the controversy that surrounded the season on finale night. It came as a surprise to the oblivious houseguests, including one finalist, Spencer Clawson, who asked, “Did I say anything Julie?” Chen responded, “We don’t have enough time.”

The controversy did not spill over to Big Brother 16, which had no similarly unpalatable contestants.

The new cast of Big Brother 17 includes one transgender contestant, Audrey Middleton, a first for the U.S. version of the show. Among the other cast members is professional wrestler Austin Matelson, who competed as Judas Devlin, and reported abusive tactics of one trainer. Matelson now speaks out against bullying.

As for Aaryn Gries, she announced her engagement last summer and got married earlier this month. She now goes by Aaryn Williams on social media.

Julie Chen also commented to THR that Big Brother producers cannot step in for the sake of the game.

“It was ugly, but you have to sit back and let these things happen. But there’s a human part of all of us behind the scenes; we think we can’t let any of these houseguests get in harm’s way. Often these people are their own worst enemies.”

Big Brother 17 airs a two-night premiere Wednesday and Thursday, June 24 and 25, on CBS.

[Image via Entertainment Weekly]