How can you tell when a god is mad?

Answer 1

Answer
I would assume that the meaning of "mad" is insane. In this case God (the one within the Abrahamic religions) cannot be mad, since for any abnormality criteria you require a notion of normality and He is beyond comparison.

Answer
If you mean 'angry': If you believe that gods get angry and show it in tangible ways, then your readily accept that every event around you is at the hand of some god, pleased or angry. You need no explanation or proof. If you do not believe in gods, or that gods would do that kind of thing, then no amount of evidence will convince you.

Answer

If by mad you mean insane or crazy, it is impossible to tell, since being abnormal first requires normality - you can't say it's broken if you don't know when it is fixed or working either - and we don't know what the mind of any god is really like.

If by mad you mean angry or displeased, then any negative event that happens to you (you lose your keys after saying "God damn it, I'm late"), to someone you know (they get in a car crash after hurrying to pick you up while you are late), or to humanity in general (an earthquake or tsunami destroys the city you live in on the day you are late and cursed a god for it) would be a good sign of a deity's anger.