That's an important consideration. If the only way to get past Bayesian filters
is to write spams more cleverly, we've made spamming a lot harder, because
we've shifted the burden of cleverness from the few comparatively smart people
who write spamware to the large number of stupider people who write the spams.

	-- Paul Graham, in "So Far, So Good"
	    <http://www.paulgraham.com/sofar.html>