If my flight shows as delayed on the board or website, I usually try to find out the reason behind the delay - I first see what gate my plane is departing out of and then try to backtrack the flight by searching what flight is arriving into the same gate. If I see that the times match up and then originating plane is still in the air on its way, I feel more comfortable. Obviously, this is not 100% infallible, as it doesn't account for plane swaps or delays once the plane is sitting at the gate, but at least it gives me some information.