Why most contestants don't make it onto The Bachelor

A new book that lifts the lid on America's top-rating reality show The Bachelor includes some startling claims.

Among them is this: the top reason for wannabe contestants not making it onto the show is that they have herpes.

The book, Bachelor Nation: Inside the World of America's Favorite Guilty Pleasure, by Los Angeles Times staff writer Amy Kaufman, isn't due out until March 6.

But an excerpt published by the New York Daily Post reveals some juicy details about the reality show, which has run for 22 top-rating seasons in America, and three in New Zealand.

Contestants go through several rounds of intense scrutiny to be on the show, including a 150-question personality test, private interviews, sessions with a therapist, and a panel interview in front of two dozen producers.

Once they're on the show, the intensity increases. The book claims they "sometimes sleep 12 to a room in bunk beds," and aren't allowed contact with the outside world - no music, book, magazines, exercising or news.

But the most startling claim is that many contestants aren't allowed on the show because they test positive for STDs.

"As soon as the medical tests came back, you'd see that herpes was the biggest thing," said Ben Hatta, a former assistant on the show.

"And sometimes you'd be the first person to tell a contestant that they had herpes. You'd be like, 'Uh, you should call your doctor.' Why? 'We're not going to be able to have you on our show, but you should call your doctor.'

"Then they'd realise they'd been denied from The Bachelor and now a bunch of people knew they had herpes."

The book also reveals that producers would let potential contestants pass through the psychological testing rounds if they looked "kind of unhinged".

"There's psychological tests they have to pass, but there's a window of the pass, do you know what I mean?" said producer Michael Carroll.

"You'd know there'd be a possibility of [someone] being kind of unhinged — like, she passed, but just barely.

"You can see it at the casting events during the interviews: 'Oh, this chick is going to go ­f***ing nuts. She's amazing'."

Kaufman's book is due for release on March 6. Read the full excerpt here.