Well, if all he can accuse her of is personal ambition and a desire to use her (former) position(s) to gain personal wealth it’s rather a case of pot/kettle/black, no?
Well, yeah ... but fairly or not, it also makes her look mercenary and ambitious, which is at odds with the "selfless servant, chosen of God" image that many of her devotees like to portray.
More than that, too: if Mr. Bailey's book says what I predict it will, he's going to paint Palin as not only ambitious, but also as a cynical and vicious politician who used the author himself to do her dirty work.
And if he's really got genuine e-mails to back up his claims, he could spin a story that spells real trouble for her.