DoctorLarry:
"Can the mods/admins catch them?"
"Well, they try, but it is hard".
You can send a message through Customer Support but you will likely need some backup - more than just a suspicion.
How hard (both do they try and is it)? Take the Wolf Creek championship for example, five tied on 59 but I could only be bothered looking at three.
One joined on the 4th and has only played only on that day, got to Pro and then playing CTTH. Strangely has a friend who joined on the 3rd and only played on the 3rd and 4th, getting to pro and then playing CTTH. The two of them have another freind in common.
Another joined on the 13th of this Month, the third joined early this month and immediately averaged a shade under 60 in his hack rounds.
Of course all of the above could be a combination of coincidence and talent ;-)) So unless you're in the room with someone who is cheating how do you provide "backup"?