Even though she says "you know" a lot -- I mean, A LOT -- doesn't mean she's an idiot or unqualified to be a senator.
There might be other reasons why she shouldn't be a senator, but her verbal tics shouldn't have anything to do with it. There aren't any other signs that Caroline Kennedy is somehow a doof -- not unlike President Bush or Sarah Palin who have each proved on numerous occasions that, in addition to their ridiculous speaking styles, they're both dumb stupids. Kennedy passed the Bar, co-authored two books, edited numerous others and, to date, hasn't used the phrases "position flexible," "you betcha" or "peeance freeance" in public.
Additionally, there are a crap load of royally doofish senators who have served multiple terms. And yet "you know" is disqualifying her? Former-Senator Ted Stevens thought the internet was a series of tubes, while at the same time serving as the chairman of the committee tasked with regulating the internet. Hell, Dan Quayle was a two-term senator.
You know?