I've noticed that when my wife opens the passenger door on my hatchback the dome light becomes way more brighter than if only the drivers side door was opened. I also noticed that the dome light is way brighter if I turn it on at the switch on the ceiling compared to the drivers side door being opened... anybody know why this is?

 

the black plastic switch in the door frame is probably rusty.a philips screw holds it in, wire brush it down and it should help