"while the youngsters, whether very talented or mediocre and sometimes awful do well by getting the teenybopper votes"

I don't think that is necessarily true. For instance this year Ellie the 16 year old girl who was pretty good and tipped by most of the judges to win went out quite early in the show whilst the older guy Chris from Liverpool (who wasn't in her league) went through to the final 3. The other 2 in the final 3 probably deserved to be there but I am still bemused as to how Chris got that far. It certainly wouldn't on the back of teenybopper votes. Likewise the US version was won by an older country singer who was good but wouldn't have picked up the teenybopper vote.

There are some differences between the US and UK shows. The US show had children in it whereas the UK has a minimum age of 16. There were some pretty good child singers in the US show but the results process was a bit too much for one of them in particular. The US show showed the voting stats every week whereas in the UK they don't do that until after the competition. The US show has slightly different categories and there is a lot less bitching between the judges so I think Cowell has many seen how that is starting to have a negative impact in the UK. There were no joke contestants in the US version. In the UK there always seems to be one contestant who obviously isn't that good or is a bit of a joke figure. ie think Rylan, Wagner, the Chinese lady, Jedward etc.