The results of a study on spam(and scam) source were briefly discussed in an article at PCWorld. Some key facts from the report includes:
1) Spam and Scams are often linked together.
2) The study identified more than 2,000 distinct scams hosted across more than 7,000 distinct servers.
3) Scam servers tend to be based in the US
4) A single takedown of a scam server or a spammer redirect can curtail the earning potential of an entire spam campaign.
The report appears to conclude that breaking a scam server will break the earnings of scammers(aka spammers). Perhaps the significance is that there is no worry about breaking a shared hosting server environment that contains other legitimate sites – which could act as a collateral damage.