I'm mixed on this too. On one hand, I want for her to succeed and she has the type of voice that thrives on "Idol" - big and belty and she can sing a lot of ballads. On the other hand, I was very critical of people like Carly who were coming in having had their fair shot at stardom before (although I also thought Carly should have been ineligible because she was signed to a company that was then run by Randy Jackson and I think that's a conflict of interest). Although I didn't think she deserved to win, she was pretty much doomed from the get-go when all of the stuff about her previous record deal came out and a lot of people felt the show was being dishonest by not being upfront about it from the beginning. I would hate for Joanna to go through those behind-the-scenes machinations as well when she will probably have more experience than a lot of other people trying out.
Either way, I hope Joanna doesn't take her making "Idol" as the be all, end all. There are two or three audition rounds before you even reach Randy, Paula and Simon and it's totally luck of the draw who makes it through those unless, as someone said above, she has already been scouted for this season. If she looks at it as just another opportunity to make her voice heard and goes in with no expectations, it could end up being a fun experience.