they have to put some truely bad acts through to reduce the competition. With 8 acts in one night, if they're all equally good there's no way to manipulate the voting audience to vote for the "right" one.
And if all else fails, ITV is no stranger to phone vote rigging .
Smartiejake how good you are has no bearing on whether you make it through to the x-factor finals. it all has to do with whether your face fits/whether you have a sob story which will indeer you to the public.
Having auditioned for x factory this year I can tell you that good acts are rejected without being given a reason why (and I'm not referring to myself, but some of the groups I heard and who obviously did have talent but didn't get through).
Would be interested to know if bgt does their auditions in the same way, ie three auditions before getting through to "audition" in front of the live audience and the judges. Am ve tempted to apply next year to find out.