I've created a topic on the Bungie's foruns with suggestions on dead ghost hunting. Please help this get noticed by Bungie, by doing a upvote if you agree and like these ideas! Thanks! I'll also put them here, but please drop by the topic to leave your upvote there as well! https://www.bungie.net/en/Forum/Post/162304023
Make instanced areas like Strikes accessible while patrolling: several ghosts hide in areas accessible only by doing strikes. Problem here, is that the fireteam doesn't want to wait for a guy scouring every corner for a small light, which makes it very difficult finding these ghosts. After doing a Strike, eg S.A.B.E.R. strike, that area should become open while patrolling so we could go and find the dead ghosts inside.
Pull out your ghost to scan the surroundings for a dead ghost: whenever we pull out the ghosts, he does a scan on the area. If any dead ghost was to be caught in this area scan, our ghosts should give notice of this.
Notice when entering a zone: if the previous suggestion seems to be too much facilitating, then another one could be when we enter a area like Forgotten Shore, our ghost would give a notice saying that it's detecting one of his dead brothers in the vicinity. The Dead Ghosts still have some kind of energy left in them, otherwise they would not be emitting a light. If our ghost can communicate from Saturn's orbit with no lag, surely it can detect a numb brother in a enclosing zone.