A few months ago, I tried to update my info for Poets.net, and they insisted that I had to place an Alexa Toolbar on my site, which I refused because I already have Google and Yahoo.
I tried to tell them that my Whois info was up-to-date--I even sent them a link to my Whois.
They refused.
Meanwhile, the contact info for my site on their site is totally incorrect.
I'm not sure why a company would not want to update its information.
So I really don't depend on Alexa for much of anything.