Index: wp-admin/includes/class-wp-ms-users-list-table.php
===================================================================
--- wp-admin/includes/class-wp-ms-users-list-table.php	(revision 17488)
+++ wp-admin/includes/class-wp-ms-users-list-table.php	(working copy)
@@ -134,20 +134,21 @@
 	function display_rows() {
 		global $current_site, $mode;
 
-		$alt = '';
+		$alt = true;
 		$super_admins = get_super_admins();
 		foreach ( $this->items as $user ) {
-			$alt = ( 'alternate' == $alt ) ? '' : 'alternate';
+			$alt = !$alt;
+			if ( $alt )
+				$class = 'alternate';
 
 			$status_list = array( 'spam' => 'site-spammed', 'deleted' => 'site-deleted' );
 
 			foreach ( $status_list as $status => $col ) {
 				if ( $user->$status )
-					$alt .= " $col";
+					$class = $col;
 			}
-
 			?>
-			<tr class="<?php echo $alt; ?>">
+			<tr class="<?php echo $class; ?>">
 			<?php
 
 			list( $columns, $hidden ) = $this->get_column_info();