Anyone else not able to find anyone with a monocle? Go to Fairfax Gardens, nope just glasses, go to Bowerstone Market, oh look imagine that, just glasses as well....
Found one. Westcliff. Look for a "noble" looking guy in a brown suit. Mine was an old balding gentleman with white hair.
The only one i've ever seen was on the quest where you are to protect Charlie. I'm pretty sure it's called "Rescuing Charlie".
Said person you are to protect had a monocle in two out of four of my playthroughs so far.