yes, most do judge based on tone of voice and whether one can carry a tune. tone is very important because it is something that i don't think can really be taught (can it?...i'm not an expert).

i christina is a vocalist like an expensive violin that may be a slightly out of tune. it's still an expensive violin. compared to most female pop singers she is a vocalist which means to me (again, not an expert) can sing outside of a studio without auto tune and other voice enhancers.

one female who i think has vocalist potential is rihanna (stop laughing). i think (like christina) she has a pleasing distinctive sound to her voice that with work could be great.

i say terrible things about britney in most threads because she's the personification of delusional over hype not only by fans but the media that aids in perpetuating a myth.