Ross, your examples are not as bad as something I found in some code I had to fix recently:

GList *list = e_vcard_get_attributes (evcard);

for (list = g_list_first (list);
     list != NULL;
     list = g_list_next (list))
{
         /* Do something */
}

for (list = g_list_first (list);
     list != NULL;
     list = g_list_next (list))
{
         /* Do something else */
         g_object_unref (list->data);
}

g_free (g_list_first (list));

“Surprisingly” it was not working, but at least it was not leaking memory as the return value of e_vcard_get_attributes is not supposed to be freed