For me, Trading Spaces jumped the shark when Kia first rolled in with her "fun" little borders. They lost me when the series shifted from home improvement to stunts and confrontations and designer temper tantrums.
And word, word, word to all the people who say they prefer to watch shows that do something for those who can't afford to help themselves.
As far as I'm concerned, Trading Spaces is what I watch when I can't find EM:Homeowner Edition, Debbie Travis, WYWO or In A Fix. (I know, I know: those last three don't necessarily benefit the less privileged. But they are FUN to watch. Fun. Not controversial.)
The only good thing left about Trading Spaces? Frank. I don't care for his decorating style. But I love to watch him work and my word is he a sweetheart!