I think the fact that Bush has worked with Miers and personally knows knows her says more than an impersonal vetting process.
Just look at Souter and Kennedy to see that lying to get the job or relying on recommendations from acquaitences is more risky.
I've worked with many people for 20 years - none of them "know me". its a business relationship that they have - she works for Bush.
Yet there are still those who think Rafael Palmeiro took steroids even though they don't even know Palmeiro and the President knew him well and believes Palmeiro's clean. And those are probably the same anti-Bush people who don't believe Bush's assertion that Islam is a "religion of peace".