Shes not an awful singer, she has said herself that she wasn't good when she auditioned for Popstars but GA sing live ALOT now, alot more than most acts & they can all sing, they've all majorly improved since the Popstars days.
As for Cheryls acts being better than her, Cheryls got a job to do, shes been asked to be a judge/mentor, shes doing that, if she was going around saying shes better than her acts then fair enough, slate the girl, but she isn't saying that, & she never would.
As someone said in here, at least Cheryl is spending time MENTORING her acts, shes been in their shoes, she knows the score, & shes more in touch with music today than the other 3 judges put together