Spotting a Multi

I'm sure this has been covered before but I couldn't find anything definitive, and I think it might be helpful to us new members.
Q: How are you able to spot a player with multiple accounts when you are playing?
I've been branching out from 1v1 and speed into regions where I'm playing more casual games with non-premium holders. Over the months I've killed time between turns in speed games (glares at the deadbeats
) reading posts in Cheating & Abuse Reports. Not in order to foe players since I have zero in that category but, frankly I find it more interesting reading than this Board late at night. Anywho... I'm amazed at how often, you, my esteemed fellow players recommend KA run a mutli-scan on a player and later I see the words: BUSTED at the end of the search.
So what twigs you to this notion? I'm figuring it might be good to know.
Cheers.
E.
Q: How are you able to spot a player with multiple accounts when you are playing?
I've been branching out from 1v1 and speed into regions where I'm playing more casual games with non-premium holders. Over the months I've killed time between turns in speed games (glares at the deadbeats

So what twigs you to this notion? I'm figuring it might be good to know.
Cheers.
E.