When I reviewed it last year I described Twit Cleaner as seriously useful. That’s because it sorts potentially bad Twitter accounts into categories making decisions easier.
Developer Si Dawson explains why he closed Twit Cleaner in a goodbye blog post. It boils down to running out of the number of API calls his service can make to Twitter at any moment.
Sadly Dawson also blogs about the upgrades he would have made if the project continued. They sound great.