While they are all about Obama, they're all debunking negative rumors and chain mails. If anything, I'd say that reeks of a serious pro-Obama bias. However, I've generally found them to be pretty reasonable. I think it's just that the conservatives have been busy spreading falsehoods around.
Another possibility is that their are just a lot more conservative pundits than liberal ones, and bogus statements such as those tend to be the flawed interpretations of people who get paid to talk about politics. It'd be nice if they explained how these rumors got started. I suspect you'd hear plenty of the same names popping up quite a bit.