public function clean_passwords( $start = 1 ) {
		$has_delete = false;
		$query      = $this->wpdb->prepare( "SELECT user_id, meta_value FROM {$this->wpdb->usermeta} WHERE meta_key = %s LIMIT {$start}, {$this->max_rows}", '_bbp_password' );
		$converted  = $this->get_results( $query, ARRAY_A );

		if ( ! empty( $converted ) ) {
			foreach ( $converted as $value ) {
				if ( is_serialized( $value['meta_value'] ) ) {
					$this->query( $this->wpdb->prepare( "UPDATE {$this->wpdb->users} SET user_pass = '' WHERE ID = %d", $value['user_id'] ) );
				} else {
					$this->query( $this->wpdb->prepare( "UPDATE {$this->wpdb->users} SET user_pass = %s WHERE ID = %d", $value['meta_value'], $value['user_id'] ) );
					$this->query( $this->wpdb->prepare( "DELETE FROM {$this->wpdb->usermeta} WHERE meta_key = %s AND user_id = %d", '_bbp_password', $value['user_id'] ) );
				}
			}
			$has_delete = true;
		}

		return ! $has_delete;
	}