Without a doubt, one of the hardest parts about working any job undercover is making sure you don't break your front, even when you find yourself in deeply compromising positions. Being able to keep cool in stressful or morally terrifying situations is one of the job requirements for any working as a detective, undercover cop, or really any job that requires clandestine action.
Since secrecy is the whole point of this line of work, it's rare us outsiders get a scoop of what it's like on the job. But the anonymity of Reddit, and internet forums in general, provide a place where people can exchange stories without blowing their cover.
IDK if I'd count this as me being undercover but I'll give it a whirl.
I used to own a game store where we buy and sell MTG cards in Maryland. There was a big tournament in Pittsburgh the weekend before where someone's collection was stolen, worth a few thousand dollars.