I prefer my motion sensor idea, where you get a motion sensor item, use and then a fallout-ish map pops out showing the area and people moving around (like the motion sensor in the original fallouts) and your character can't do anything else at the time. The idea is to simply detect movement, no further identification. X-COM (the original, not the travesty remake) had a similar device, and the more something moved on it, the bigger it showed.
What is that red dot moving across the map? Sneaker? Looter? Critter? Scav? Teamate? Its up to you to identify!