This is a pretty old thread, but I just had this issue with SimpleSearch and wanted to help by adding my solution. While Susan’s Property Set solution works (I assume, I haven't tried it), it is rather an impractical method if you have a large site with many different MODx tags within the content.
I simply wrote an output filter for the extract - (i.e. [[+extract:stripMODxTags]]).
The "stripMODxTags" snippet:
$output = (string) $input;
$regx = '/`[\w\W^`]+`/i'; // strip anything between ticks including ticks (``)
$output = preg_replace( $regx, '', $output );
$regx = '/\&(amp;)?[a-zA-Z0-9_\-\.\?^\=]+\=/i'; // strip remaining tag qualifiers ( &tag= )
$output = preg_replace( $regx, '', $output );
return $output;
This seems to work fairly well (we’ll see, I just wrote it). I’m not really a Regular Expression guru and I haven’t extensively tested this, so if anyone has improvements to the Regular Expressions, that would be welcome. Thanks!