anti-ad blocking (anti-leech) system?

[Spinball]

Zero Tolerance seems to have disappeared (?!).
Ok, I implemented a solution where a div tag is put around the advert and put the following Javascript after it:

<script type="text/javascript"> <!--
if (document.getElementById('AdObject')=null)
{
var nagtext='<H3 align="center">Nag message.<br>Thank you.</H3>';
document.write(nagtext);
}
//--> </script>

and installed AdSubtract software to block adverts. My solution above failed because AdSubtract adds

 style='text-decoration: none'

at the end of the IMG tag of the banner.

Anyone know how to detect the text-decoration setting of an element? If I could detect that I could also display the nag message.