How Bad Are Singletons?

Question

So ....

There are obviously many questions that all have been asked about Singletons, Global State Variables, and all that great stuff. My question is,

Answer 1

In the process of cleaning a Singleton would represent hiding the dirt in the dark corner instead of cleaning.

It's so widely used because it does it's job of hiding problems very well.

It's a good thing for those who are to clean, but don't want to.

It's a bad thing for those who are up to actually clean something.

Consider Dependency Injection http://martinfowler.com/articles/injection.html if a Singleton is causing a problem you can't hide anymore.