TwitCleaner, the excellent service to help you manage your twitter account, has shut down due to inability to maintain service following upgrade to Twitter API 1.1.
Check out the list of features planned to be implemented and now look at how well, in five years, twitter has managed its spam problem.
It looks like developer Si Dawson nailed it when he wrote;
So obvious in hindsight. Never play football when someone else owns the field.