Scraper_Class {
    var $title;
    var $url;
    function fetch_content(){
        $this->title = $this->get_remote_title();
    }
    function get_remote_title(){
        //...
        return $title;
    }
}

Website_Preset_Class extends Scraper_Class {
    static function can_load_url($input_url){
        //...
        return true;
    }
    function get_remote_title(){
        //...
        return $title;
    }
}

function get_scraper{
    $scraper = new Scraper_Class();
    foreach($presets as $preset){
        if ( $preset::can_load_url($url) ){
            $scraper = new preset();
            break; //we've got our preset
        }
    }
}

Scraper_Class {
    var $url;
    var $title;
    var $filters;

    function fetch_content(){
        $this->title = $this->get_remote_title();
        //...
        $this->remove_temporary_filters(); //<-- HERE
    }

    function get_remote_title(){
        //...
        return apply_filters('get_remote_title',$title);
    }
    function add_temporary_filter($tag,$function_to_add,$priority = 10,$accepted_args = 1){
        $this->filters = array($tag,function_to_add,priority);
        add_filter($tag,function_to_add,priority);
    }
    function remove_temporary_filters(){
        foreach((array)$this->filters  as $filter){
            remove_filter($filter[0],$filter[1],$filter[2]);
        }

    }
}

Website_Preset_Class { //not extending Scraper_Class
    function __construct($scraper){
        if ( self::can_load_url($scraper->url) ){
            $scraper->add_temporary_filter('get_remote_title',array($this,'get_preset_title');
        }
    }
    static function can_load_url($input_url){
        //...
        return true;
    }
    function get_preset_title(){
        //...
        return $title;
    }
}