Gay, frequently. Psychiatrist, occasionally. Scandinavian tourist, more often than I can count.
I don’t really fit the demographics of my neighborhood. A week after we moved in I was out working on my fence (imagine Carhartts, pickup, tools, etc). The neighbor across the street stopped her car beside me and rolled down her window. She pointed to my house and asked: “How much is he paying you an hour? We’ve been looking for a good handyman.” 
“Well, I’ve got his credit card, and I sleep with his wife…”
I get mistaken for a man much of the time, it seems to be related to me being tall and having the temerity to wear my hair short. It was especially annoying before my breast reduction surgery when someone would address me as sir while my E cups were spanning the gap between us.
I’ve been mistaken for a homeless person, while dumpster diving.
In college I worked in one of the school’s libraries and without fail almost every shift someone would approach me speaking Spanish. I do tan pretty easy and have a slightly…very slightly darker complexion but I definitely don’t look Hispanic yet it almost always happened.
I’m a cashier in a store about a mile from a Target, and we also wear red shirts. I learned early on not to wear my red shirt in Target.
I’m also mistaken for “Judy” a lot.
I worked for a woman who drove a black van. She was often called “Jade.” One day she saw a woman get out of a black van. A woman whose resemblance to her was remarkable. She stopped her black van, got out, walked up to the woman and said “Jade?” The woman replied 'You must be Joanne."
They became fast friends. It runs out Joanne was a real estate broker, and Jade was a mortgage broker.
I had a Hispanic man tell me I have a beautiful Hispanic accent ! LOL! I am hard of hearing and have a HOH accent ! This happen to me in Mexico too a
Hispanic woman overheard me talking to my b/f and she can running over to a started talking to me in Spanish . I had no idea what she was saying . Some people think I am Hispanic .
I was mistaken for a food critic. I was working as a server tech, and doing a site survey at a McDonald’s. When I was taking pictures of all the equipment in the store, somebody asked me if I was a food critic.
This. I was once mistaken for a ShopKo employee while I was shopping there. I was in full goth gear, mini skirt, hooker boots, multiple facial piercings, way too much eyeliner, and this little old lady got mad that I didn’t know where some snack was located. At first I thought she was just asking if maybe I’d seen it while I was shopping, but no. She genuinely was under the impression that I worked there, and that they had a very lax dress code.
I also had one regular customer (at the store I DO work at) who- on multiple occasions- told me that I used to be friends with his son, whom I’d never heard of. He was quite insistent about it.
In my late 30’s I was working for a company filling vending machines. After work one day, still wearing the company uniform (navy pants and light blue shirt) and carrying about 40 keys hanging from a ring attached to my belt loop, I stood outside a library. A man approached me. His first words were “Excuse me officer…” then went on to describe a problem with his vehicle. He thought I was a policewoman.
You better hope nobody mistakes you and your client for one another when the bailiff comes to take one of you away.
Suggested reading: “Equal In Paris” (short-ish essay) by James Baldwin. (See if you can find a good clean copy on-line or somewhere. All I found was a rather dirty and poorly scanned PDF.)
A zoo employee.
Granted, my parents did, at the time, own the zoo I was in, but I was 10.
I also get mistaken for a local pretty much anywhere with a large white population; apparently I walk like I know where I’m going, so I get asked for directions everywhere I go.
I’ve been mistaken for a cop, paramedic, military officer, and other public “helping” professions. I think it’s because I’m a big, tall woman with good posture (and, as a friend once said, “you walk like a big guy”).
I have also made the fatal error of wearing a red shirt and khaki pants to Target. Oddly, though I’m not wearing an orange apron, I’ve also been approached in Home Depot by customers. Butch chick = hardware expert (?)
****Family story *****
My brother, Josh, was a dead ringer for Bodie, a kid around the corner. Bodie was two years older than Josh and, one day, ran away from first grade and went home.
Josh was happily playing in our front yard when the school secretary, dispatched to scoop Bodie back up and return him to school, cruised by and saw a little kid that matched the perp’s description. Josh was hauled in and seated at Bodie’s desk before the teacher realized that it wasn’t Bodie.
Josh was returned home and the real Bodie was taken back to school. We didn’t know what had happened until Josh mentioned at dinner that he “went to school today” and the story unfolded.
Note: we lived in a small town and this was 1973. Kids ran free and feral in those days and the fear of “stranger danger” was not instilled in us; therefore, when the school woman pulled up and said to Josh “get in the car, Bodie” he happily complied. The same for his return: he was just dropped back off in the yard.
I mentioned in the OP that I get mistaken for a construction worker. If I’m not going into the office or some social event I’m wearing old clothes, often spattered with paint or torn and I guess my build doesn’t spell software engineer, so hanging around town locally several people assume I must have come from the job site. A couple of guys I have become friends with were contractors who offered me jobs. It’s that book cover thing.
Patients frequently mistake me for their nurse, even after I tell them I’m their respiratory therapist. I’ve been taking care of the same patient for two months now and he still insists I’m his nurse. Them again, the doctors and nurses think I’m a nurse too.
I suppose your parents didn’t even get a receipt.
Me too eh.
I was mistaken for a prostitute one night in San Antonio. I was sick from sunburn and leaning against a cool building when this middle-aged man asked if I wanted to “party” with him.
I have been mistaken for Anthony Michael Hall 4 or 5 different times, over a span of two decades.
I was mistaken for a woman (I had long hair and someone said ‘scuse me luv’). I was soon after mistaken for a neonazi skinhead (I had shaved my head to raise money for charity).
Some years later, I was mistaken for Prince Edward.