Her singing has won her many fans, including her idol, British theater legend Elaine Page.
"She's a country girl, and I think she just has the most lovely, natural voice," Page said on "Good Morning America." "She's very open in her performance. ... In such gloomy times that we're all sort of living through at the moment, economically speaking, she was a breath of fresh air."
Even as some in the media have speculated if Boyle may be too good to be true, Ruffel insisted, "She's definitely the real deal, sweet innocent Susan."
But Boyle confessed in her interview with "Extra" that she was just joking when she told Cowell that she had "never been kissed."
"It was meant as a joke," she said. "I've got a wicked sense of humor, you know!"
Still, British cultural critic Shane Watson said the fuss over her comments was unwarranted.
"The point is, even if they do groom her up -- and why not -- and even if she was joking when she said she'd never been kissed, it doesn't detract from the fact that she is an ordinary woman, unglamorous, unmarried, unsophisticated, unworldly, and of a certain age, and as such she is a breath of fresh air," Watson told ABCNews.com.
Ruffel said the attention hasn't changed her friend at all.
"She's still Susan," she said. "She was in here the other day, and we were saying to her, 'Finally you made it.' And she said, 'I don't know what all the attention is about, I just wanted to sing."
"You won't change Susan," added Ruffel. "We have a saying here: You can take the girl out of Blackburn, but you can't take Blackburn out of the girl. She'll stay the same with her feet firmly on the ground, a sensible girl."
After the results were announced on Sunday night, Boyle said she felt "fantastic," adding, "What pressure? I've really enjoyed myself tonight."
The Associated Press contributed to the reporting of this story.