I've been thinking about this a lot. There are thousands of screeners and filters out there, but most people I talk to either:
1. Use default screens they found somewhere
2. Built their own but never really validated them
3. Just trade whatever's in the news
For those who use screens/filters as part of your process - what makes you trust that the criteria you're using actually gives you an edge?
Is it backtesting? Forward results? Just gut feel after years of trading?