By far the worst offenders are Christian children's shows. Having worked for a Christian publisher, I saw more poorly-produced shows than I'd like to admit. Cheesy accents, enormous mis-matched mustaches, over-pronounced words, and perky songs about nothing. Throw in a puppet and you've got yourself a best-seller.
The only Christian children's show I can bear to sit through is Veggie Tales. Smartly written, there are often jokes aimed just at the parents. It's obviously still geared towards kids, but it's not nearly as obnoxious as other offerings. Kids can learn from shows without hyper-color cheesiness. Don't insult their intelligence.