I’ve never noticed any particular scent when we’ve been away for awhile and then returned. I have, however, noticed cooking smells with particular items, usually something that has to simmer or roast for a long time:
Since we like these things, it’s all good 
In the spring, I also will buy hyacinth plants and put them the kitchen, so that would be the first thing you’d notice then upon walking in the house.
As it happens, I just got back from a short trip today, and noticed an odd scent in my home–acrid, sort of bitter. Reminds me a little of pesticide. I’m still catching little whiffs of it, though my nose has mostly tuned it out. I don’t like it, so I’m going to try to figure out what’s causing it, but it’s going to be difficult if I’m nose-blind to it.
I got worried, because I smelled that in our apartment, but very, very faintly. It was the smell of wires shorting out. I checked everything possible, and turned off everything we didn’t need, including breakers to the back of the apartment. I tested everything with a multimeter-- every appliance and outlet. Nothing. It seemed to be coming strongest from a wall that didn’t have wires for our apartment in it. I assume it was something from the neighbors, and it was gone the next day. It’s possible they were cleaning their oven; more likely an appliance failed. Or their kid has an erector set with a motor. or a train set, and burned out a motor, or set a small fire accidentally using solder.
That’s one thing I hate about apartment living, which I mostly love, after looking after a yard for 12 years, and being responsible for all the repair bills. Neighbors make worrying smells and noises.
Was a fun little game I used to play with our kids. I’d give 'em half a hug, sniff their heads and tell them where they’d been.
Wasn’t hard. Their friends’ houses had really distinctive smells, as did the fishin’ hole and the woods. And the chocolate shop? Wasn’t all that difficult…
Cat odor. Sigh.
It’s not electrical in the case of my place. I was an electronics tech and engineer long enough to have a whole catalog of smells from burning electrical stuff, and this doesn’t match wires, ballasts, dusty resistors, or any of the rest. I think it may be a faint scent some lawn chemicals in the garage are giving off in the heat.
Exactly the same at a friend’s cottage that has been in the family for generations. The latest batch of kids are all long grown up and long started their own families, but there are still height marks on the door jambs recording their growth, and huge numbers of their kids’ books and grownup books around. Most of the really old books have a slightly musty smell that I always associate with cottages, and there are lots of old magazines with the same scent. No, you’re not weird, and smells can be powerfully nostalgic. The musty smell of old books, the smell of beach and sun, are all wrapped into my cottage memories.
I agree that each occupied house has its own scent. About eight months ago I purchased a refurbished 1969 Magnavox console record player/radio. Once it came upstairs the living room took on the scent of a musky old 1969 appliance.
I love the thing but I will admit I could do without the scent. On the other hand all my visitors love it when I put on a real vinyl record and Tony Bennett or The Chairman of the Board belts out a tune.
Every room is my house has a different odor. The garage smells of oil and garbage and leaves and grass. The laundry room smells of cat box and concrete. The living room smells of wool and books. The dining room of plants and electronics. The library of books and faintly of at supplies. My bedroom smells of the cellulose insulation in the nearby attic, but if we haven’t done laundry in a while it smells of people. My daughter’s room always smells like her. And everything smells of room freshener after the cleaning lady comes.
One of the memories from my childhood is visiting the homes of older relatives. Their houses/apartments always smelled of old cooking oil, onions, garlic and spices. These homes invariably had decades-old wallpaper that absorbed everything that was ever cooked there.