Smileys are evil :-) Some people use them instead of standard interpunction ;-) Those 'fancy emoticon images' always brake baseline grid :-) Typographers worst nightmare ;-) :-) Furthemore, it draws attention away from the text, so it is more difficult to read :-)

Images used (shamelessly stolen):
 - http://blog.php-group.cz/wp-includes/images/smilies/icon_smile.gif
 - http://blog.php-group.cz/wp-includes/images/smilies/icon_wink.gif
Smiley-infected interview that served as an inspiration (made me angry by its design, but amused me a lot by its content):
 - http://blog.php-group.cz/2008/04/01/prednaska-o-frameworku-nette-david-grudl/
Userstyle redeem (try of):
 - http://userstyles.org/styles/9674