It bothers me more when people on the "real" talent shows have the advantage of previous record deals etc. I'm thinking of the horrendous Andy Scott Lee (3SL) and didn't Lemar have a deal once as well before his FA days? I think the same goes for James Fox - certainly some of them had a lot more performance experience than others.
Unless you take all of the Comic Relief students from celebs who absolutely can't sing OR ones who definitely can (and I would find either option very very dull) - it's not going to be a level playing field, but really, it doesn't matter. If people resent Kim's previous experience they can show this by not voting for her. If people love Reggie for having a go even when he is tone deaf, they are free to vote for him. At the end of the day it doesn't really matter why people vote, as long as they do. I don't see any of the more vocally challenged students resenting those who clearly do have training and ability.
Of course Kim wants to win. She isn't stupid. She knows this will help her develop the musical side of her career and good luck to her. At the other extreme of musical ability, it wont have done any harm to Reggie's presenting aspirations either as I am sure I am not the only person who had no idea who he was before the programme. OK, I don't particularly like him but he will have made a lot of new fans and raised his profile in the area that he wants to excel.