When do you believe "anonymous sources" and when don't you?

“Anonymous sources” seem to be used very opportunistically.

If a sensational story cites “anonymous sources” do you believe it if it aligns with your political views? Or are you skeptical of all stories that cite only “anonymous sources”?

I’m not saying stories that cite anonymous sources should not be published. There are important stories and scandals that may have initially gained proliferation through anonymous sources. I’m simply asking what kind of trust you place in them?