JPJA
18
This address has redeemed all multisig dust:
http://blockscan.com/address/1BADaNiGQ3GuF8Fb35oWpym4KfzLCbHvYb
Example redeem transaction:
https://www.blocktrail.com/BTC/tx/f4e2d186ed56aad9b965370411cece4e65fb8dba33ba04d03295299c273e527f
And indeed, http://redeem.bitwatch.co/ indicates that this address has
0 unspent outputs
Maybe it’s possible to figure out how they did it by studying the redeem transaction?
Check this funny thread. People were giving out passphrases with multisig dust and someone did indeed sweep them