A Times report suggests that, in spite of the Palins' (yes, Bristol too) efforts to keep the family in the news, each outing lasts for a relatively short time.
...There was sobering news on Tuesday about one of Ms. Palin’s other products, the reality show “Sarah Palin’s Alaska.” In its first week the series drew nearly five million viewers to TLC, the highest-rated premiere ever for that channel. But in its second week the series suffered an unusually steep ratings drop, to about three million viewers. In the 18- to 49-year-old demographic, her audience dipped to 885,000, from 1.8 million the premiere week.
In other words, plenty of Americans like to check in to see what she's up to, but not many stay.