It is being reported lately that spammers are using lesser known domains in their links in spam messages. See this article for example. In the article they state:

Using a lesser-known top level domain changes the game and makes it harder to distinguish spam from legitimate e-mail by examining the links in the e-mails.

They also quote Conor Flynn of Irish security firm Rits as saying:

"Spam filters are set up to recognise the well known domains, spam from lesser known domains can slip through"

I would have to disagree with both of these statements. It actually might make it easier!!