Spamcalc takes a hostname or a list of hostnames and determines a dns spam
score for each hostname.  This value is an indication for the spam-ness of the
hostname.  The higher the score, the higher the chance that the hostname is
actually a dns spam hostname.

Hostnames that are considered dns spam are hostnames with (a part of) a
sentence in them (master.of.the.world.net), swearwords
(shittywhore.armaster.roadkill.net) and other forms of unwanted textual data
(666666666666666666666666666666666.sixtysix.org, 0-1-2-3-4-5.blah.com).

WWW: http://www.garion.org/spamcalc.php