[valdet]

Needless to say that if you just add a simple text like Image: on top of embedded images, you will prevent invisible/transparent images, used as links.

PHP Code:

return 'Image:<br /><img src="' .  $link . '" border="0" alt="" />'; 


We had an interesting situation where one spammer was inserting 1x1 px. images and linking them to his site.

With that single code hack, I was able to find in which posts he dropped his link, clear them off and ban him instantly.