"Hey, your tail light is out. Won't give you a ticket this time, but please do get it fixed". Is neither harassement nor intimidation. But it does remind people that these things are noticed, and that failing to fix a taillight might actually earn you a fine.

in the case of a stop that quickly becomes a terry stop.

in the case of i stopped you because -rear lights, i see noone else has a notation on your marker, go get it repaired, right now...then your free to go,

thats how i generally see a traffic stop actually being a traffic stop.

Totally depends. It's easy to imagine a situation where responding to a noise complaint would ideally finish with a warning.