One time I was walking down a shopping street minding my own business. There was a pedestrian crossing and I was going when I heard this metal bang. Turned round and this young guy was kicking a cars door and screaming. There was a guy in the car and he looked scared.
This was pretty much a major scene when in literally 5 seconds to guys in jeans and t shirt were there putting the guy in handcuffs. They were undercover cops. They quickly diffused the situation.
At the time I was a bit freaked out. Firstly because of the acts of violence the guy did on the car and secondly it was a bit disturbing to realise undercover cops were literally walking under your nose.
But later after thought I found it reassuring the cops were there.
My parents live across the street from a park that is known for drug deals,
When I go walking over there, there are always plain clothes cops.
You can tell because they have short hair, no facial hair and always wear jeans and polo shirts ( its an athletic park and people usually wear work out clothes ),
For some reason they also always smell good.
I doubt they’re very successful catching drug dealers because everyone knows they’re cops.
In the uk there was a recent scandal where cops went deep undercover for years at a time infiltrating groups like anti nuclear weapons groups etc. But some of the cops ended up having long term romantic relationships with some of the group members. I think some even fathered children.