Look at the evidence.

Forty years in the business, choreographer for Hot Gossip - has choreographed for numerous shows and TV programmes. She knew her stuff with dance

Aleesha Dixon - nice girl but out of her depth
BBT Amanda Holden - pretty girl but never says anything useful
TXF - Danni, knows what works but not really that interesting when she is on.
TXF - Cheryl Cole, a tabloid name but never really says anything constructive
AI - Paula Abdul, mad as a box of frogs and full of incoherent mumblings
AI - Kara Dioguardi, mutters on about "being connected to the music" and "I feel you" but nothing usefully technical.

The exception to this is Sharon Osbourne but she was such a witch she didnt last very long. Compare these with Simon Cowell, Len Goodman, Louis Walsh, Craig Revel Horwood, Burno Antnononi. They know their stuff.

The excepiton is Randy Jackson who knows his way around the music business but is utterly inarticulate. The same with David Hasselhoff? But they are Americans..

So Arlene? The only one who really worked?

nicki chapman was good on popstars/pop idol, denise van outen was good on joseph and oliver, carrie grant good on fame academy

Nina Myskow was good on New Faces. Well she was just a hard nosed journalist, but I am sure Simon Cowell copied her?