everyone likes to rant around about how "block checkers do not work" well this is what they truely mean by that, what microsoft has done to disable block checkers from working. they created a check box in the options. This can be found Tools>Options>Privacy. Its labled "Only people on my allow list can see my status and send me messages". This box is not checked by default. So if the person does NOT check this box then some block checkers can actually find out thier status and current name. A lot of users tend to forget to do this. So this basically states that a block checker can do its best to provide an answer, but however may prove to be inaccurate if that user checks that box. To tell ya the truth, and its pretty bad, not too many people out side of these fourms and other tech fourms realize this.
So that is the guarentee they assure. Theres is other programs out there called delete checker, which informs you of all the contacts which have deleted you of their msn accounts. I have had success with the accuracy of this program, and even tested it out with my friend while he was online.
And I have found an accurate block, and delete checker on the web. And for the accuracy to checking blocked contacts, they explain that in full detail. This site actually does not mess with your nickname or use your password in any wrong way. I am not sure if I would be allowed to post it because they really dont enjoy much talk about block checkers on these fourms