You can report them by just pressing the "report" button, you don't need to find a thread. And those resports get handled as well (obviously).
I used to do that but last time I also posted as well as reported because there are so many people doing the same, to get merits I suppose.
"Report To Moderator" is for reporting shit post/cross post and it goes to normal moderator queue that do not have capability to ban the user.
Report to mod is for reporting anything.