Behind the Scenes of 'The Bachelor'

March 15, 2010— -- The Bachelor franchise has become a phenomenon. Behind the exotic locales, picture-perfect landscapes, and steamy shirtless scenes, a small army of producers, casting directors, wardrobe assistants, makeup artists, trainers and more, plan and plot their way to another hit season.

When ABC's "The Bachelor" began its run in 2002, everyone, including the show's creator and executive producer Mike Fleiss, was convinced an on-camera proposal was a must-have climax.

"I remember during Season 1, getting a panicked call from the network," Fleiss recalled, "and hearing on the other line that, 'Mike, you've got to do something about this! They're not falling in love!'"

As it turned out, everyone was wrong. Real love and a marriage proposal were less important to the audience than a dreamy prince charming and a cast of gorgeous, even villainous women.

"We need our fair share of villains every season," Fleiss said. "And now we're very careful in our casting...to develop characters that the audience is going to root for and root against."

Watch "Inside the Bachelor: Stories Behind the Rose" on a special edition of "20/20," tonight at 8 p.m. ET

Out of the 25 women chosen to compete for the Bachelor's affection, only half need to be sincere to make a successful season, Fleiss said.

Casting has become critical to the show's success. Contestants go through a rigorous screening process, including multiple rounds of producer interviews. The 50 finalists must take STD tests and complete an 800-question psyche evaluation.

"It can be a somewhat emotionally taxing, people don't realize how fast emotions get involved," said Dr. Catherine Selden who conducts psychological evaluations with the finalists. "We want to make sure that people are going to be OK with coping with the stress involved, and make sure that they are going to be offered the help that they need if it's the case."

Click here to see Jake, Vienna, Ali and Gia's never-before-seen audition tapes!

Contestants must be willing to discuss every single event that occurs and share every emotion that crosses their mind during their time in Bachelordom.

"If you aren't able to be vulnerable, whether it's to the person and therefore to the cameras, despite the cameras around you, you might as well go home," said executive producer Martin Hilton.