Index: includes/common/template.php
===================================================================
--- includes/common/template.php
+++ includes/common/template.php
@@ -110,7 +110,17 @@ function bbp_is_site_public( $site_id = 0 ) {
 	// Get the site visibility setting
 	$public = get_blog_option( $site_id, 'blog_public', 1 );
 
-	return (bool) apply_filters( 'bbp_is_site_public', $public, $site_id );
+	// If 'blog_public' is greater than zero, this implies the site is public
+	if ( (int) $public > 0 ) {
+		$retval = true;
+
+	// If lower than zero, site isn't public
+	// This includes disabling search engines under "Settings > Reading"
+	} else {
+		$retval = false;
+	}
+
+	return (bool) apply_filters( 'bbp_is_site_public', $retval, $site_id );
 }
 
 /**