moTi - 7:09 am on Jan 9, 2013 (gmt 0)
i remember markus in his legendary WebmasterWorld thread ("how i made a million in 3 months") mentioning, that he actually blocked alexa and comscore for competitive reasons. namely to prevent business spam and lulling competition by staying under the radar. he stated, that out of 600k visitors, only 60 had installed the alexa toolbar. and that was 2006, so probably the number is rather worse by now.
i think that's outstanding business sense and exactly the way to go about these metric sites. rather keep control of who gets to know the true value of your website. as mentioned, only an absolute moron would buy a website because of alexa stats anyway. in my experience, there are a hundredfold more potential copycats who are out for destroying your business than serious beneficial business contacts to attract.