I think that kids are not being exposed to enough "dirt" to build up healthy immune systems. Research actually shows that kids who live on farms are healthier than kids who live in town--the hypothesis is that all the playing in dirt "innoculates" them to various bacteria & viruses. So yes, I'm the "bad mom" who has never wiped down a toy unless it has visible dirt on it, I've never wiped down a shopping cart before putting my kids in it, I don't carry anti-bacterial no-water hand wash...etc, etc, etc.
And I can't managed to get my kids to catch chicken pox, even though I've exposed them multiple times. They are just too gosh darned healthy.