Here is a list I've built based on various answers from people on Twitter, IRC and other sources. Thanks guys!
We won't use your CPAN distribution if:
10. You don't care about users
Why did you even uploaded it on CPAN if you don't even care if anybody is going to use it? Why did you write your contacts if you don't ever answer questions?
9. It is not actively maintained
Several open bug reports for years don't add any trust. Not maintained code begins to rot, stays in the past and finally dies.
8. It reinvents and does not improve other distribution
There is nothing wrong with wheel reinventing as long as it's an evolution, the next turn of the helix. As long as it adds something new, as long as it provides an alternative, not a clone. The better implementation will survive.
7. API is not comprehensible
Non intuitive API forces us to open distribution's documentation hundreds times a day. We have to write an Adaptor just to make it readable, understandable and maintanable.
6. It is not backward compatible
Of course it is impossible to be 100% backward compatible, but nobody expects that. What drives people crazy is the ridiculous API changes across minor versions that break every application built on top of the module in several places without obvious reasons and comprehensible explanations.
5. It does too little
Too little does not mean more than 1 line of code. It means that there is obvious and bound to a particular case code that is not abstract enough for a separate distribution.
4. It does too much
Developers don't need complete solutions, they need flexible tools to build their own solutions. We use modules because they save us some work, not because they replace our work with a highly coupled brick that doesn't move.
3. The code is unreadable or is poorly written
It is always easier to rewrite a module from scratch than understand how the unreadable code works. With unreadable code you can't even appreciate the work that could be saved by using it. You see just a bunch of ascii characters that were typed by a monkey. Actually unreadable and poorly written code is the same thing. Why would you ever trust a module that you don't understand?
2. There are no good tests
Tests are more important than a readable code, because you can refactor it without a fear to break anything. Of course it is not always true, expecially when the test suite isn't complete. But it gives you a good starting point before writing your own tests, which has to be done anyway to make sure you understand the API and it works as expected in a particular case in a specific environment.
Tests are also a good source of examples.
1. It doesn't work
it doesn't work I mean it doesn't work in general, completely not workable
in a real life. This may sound obvious, but everything else is not important
unless the module works. It doesn't matter how many tests there are (even worse
if they pass), how clean and precise the code is. If it doesn't work why did you
put it online?
If you don't check it in a real life and are deceived by a feeling that you have 1k tests and they all pass, that's going to end badly. Fallacious confidence will lead to a situations when you trust your tests more than users' bug reports that come from the real life applications, multiple server environments and operating systems. Don't get fooled.
Are there any other things that stop you from using a specific distribution on CPAN?