Displaying Content Based On Visitor Behavior Using Web Service

I'm using javascript in addition to a web service (BTBuckets) to display different content to visitors based on actions they take on my site. The javascript is working fine, but I noticed that if I simulate BTBuckets being disabled using Firefox Adblock none of the content shows up. So in the off chance of the service going offline it'll leave some pretty funky holes in the my content. I tried <noscript> tags which works with javascript off, but the content is still blank when I disable BTBuckets. I'm wondering if there's a way to display the default content if the service is unavailable?

Here's the code I'm using:
In the head:
<script type="text/javascript">
//<![CDATA[[
$BTB={s:XXXXX};
$BTB.jsh="[URL]";
//]]>
</script>
<script type="text/javascript">
document.write(unescape("%3Cscript src='" + $BTB.jsh.replace(/(https?:)/i,document.location.protocol) + "' type='text/javascript'%3E%3C/script%3E"));
</script>

The code in the body used to replace an image depending on visitor behavior:
<script type="text/javascript">
var _t = "";
if ($BTB.clusters["ppc_visitors"]) {
_t = ""images/top-photo-tracking-number.jpg" alt="Call Toll-Free: 1-800-XXX-XXXX">";
} else {
_t = ""images/top-photo.jpg" alt="Call Toll-Free: 1-800-XXX-XXXX">";
}
document.write('<img src= ' + _t );
</script>
<noscript><img src="images/top-photo.jpg" alt="Call
Toll-Free: 1-800-XXX-XXXX"></noscript>