I would honestly extend this further.
1) If you start placing barrels explosives around an NPC, they should become aggressive as you are quite literally endangering them.
2) If you start turning off all the light sources in an area, they should start growing suspicious and turning them back on and watching you closer.
3) If a merchant has been robbed while you are present more than once, your approval should start to go down even if they don't caught you just because they are getting suspicious of how they keep getting robbed as soon as you are around.
To be honest, I think the overall merchant setup they have right now deserves an overhaul I mentioned before, but thats outside of the scope of this thread.
