I used to be able to when I was a kid, really well. It seemed like everybody I knew and their houses had very distinctive scents. Objects, too, a lot of the time; my older brother’s Boy Scout book had this pulpy wood smell to it that I could smell from across the room. I had a weirdly acute sense of smell. I don’t think my sense of smell is that sharp anymore, but on the other hand I can have a cookie anytime I feel like it now, so y’know, it balances out.
Brownies baking in the oven!
Hot cocoa.
Lily of the Valley.
Jergens lotion from the '70’s with the amaretto scent.
Freshly ironed cotton shirts.
–Beck
Ditto the Rain on Hot Asphalt smell. It smells like Six Flags and summer.
Roasting green chiles.
Raspberries.
New Barbie doll - that new vinyl smell.
Temple Incense. Lots of sandlewood and citrus. Great scent.
Guess I’m not unique. Most of these are taken.
A bakery with the door open (I’ve noticed several references to bread or baked stuff…mmmmmm!)
The scent of unsmoked pipe tobacco in a tobacconist’s shop (I haven’t touched any kind of tobacco now in 22 years, but the fresh cut stuff still smells great to me)
orange blossoms
Babies smell good… after they’ve been changed, washed and powdered. If you like them at changing time you’re as weird as mrklutz. (skunk??? Yikes!) 
a pile of leaves
fresh mown grass
a lumber yard
gardenias (for about two seconds…then the odor gives me a headache)
At least you can enjoy them all at the same time. All you need is a nice cabin in the mountains, a rainy Sunday morning, a stove and some dough, some sheets coming out of the dryer, and some pickled eggs and Pabst Blue Ribbon. 
(I love your username, by the way!) Yup, those two for sure. That Jergens scent is almond and rose water.
Also:
Autumn woods in which the scent of black walnut hulls is part of the mix
Catholic church incense
When the furnace comes on for the first time in the fall
A blend of “Off” insect repellent, earthworms, and fish slime – the quintessential smell of summer vacation
My very favorite scent is at the very beginning of a rain when the drops mingle with the earth. What a lovely smell! Makes the incense cedar out front smell really good too.
My second favorite smell is when I open up a fresh bag of peanuts for the squirrels. I stick my face in the top and take a good, deep whiff.
Other great smells:
Real yeast bread in the oven.
Fresh coffee beans.
Loose orange pekoe tea.
The way certain rocks smell when you rub your hand on them.
The sulphur smell of a lit match.
Pine woods, expecially when camping.
Pipe tobacco smoke. Interestingly, I passed by someone recently who was enjoying a bowl. It had been years since I’ve been around anyone smoking a pipe.
The beach at low tide. A few years ago I tried my first raw oyster. I was delighted to find it tasted exactly the way a beach smells. I wish I knew what variety it was because I’ve found out that not all oysters taste the same.
Old garages. Dust and dirt mingled with oil and gasoline makes for a lovely smell!
Gunpowder, catcher’s mitt
I can’t believe no one’s mentioned my favorite smell, Pine-Sol! I especially love it when I’m pregnant and will mop every day. Sometimes when I’m in the grocery store near it, I’ll open a bottle to take a big whiff.
I second the baby-head. Baby-head smells wonderful.
Creosote- a bush here in the Sonoran desert which releases a smell when it rains. Smells like… rain.
I’ve come to like the smell of acetone, because I work with it a lot.
I’ve kind of developed an obsession with smelling things. If someone at work comments on the smell of something, I run right over, “Let me smell!” Even if I know it’s going to be bad. My sense of smell is pretty acute- can other people smell when a woman is on her period, using both deodorant and plain sanitary products, or is it just me??
Rosemary
Thyme
Vanilla
Fresh bread
Sweet peas (flowers)
Peonies
Sherry
The warm, fresh blood of my enemies.
Am I nuts, or is this much more noticeable among women over 40?
Honeysuckle on a warm summer night.
Old Barns
Libraries and old bookstores
Newly mown grass that had wild onion in it
Baby hair, definetly
WD-40
Leather
Hawaiian Tropic suntan oil
Hose pipe water
Thunderstorms
Books, new or used
Roasting hops (there’s a brewery down the road from us, and when I drive past, it smells WONDERFUL)
Apples in just about any form, fresh, baked, as applesauce
Pomanders
Sun dried sheets…but I put them in the dryer for a bit because they are stiff as boards
Magnolia, wisteria, honeysuckle
Iced tea
Burt’s Bees lemon butter cuticle creme, sometimes I open the tin just to smell it
Any sort of yeast bread or pastry, but especially stuff with cinnamon in it
Rain, and the way the outside world smells after rain
Showing my age here…
In grade school, the smell of the freshly copied papers that the teacher would hand out. They smelled best while they were still warm.
The stream of warm air blowing from a computer fan.
Rubbing alcohol.
New bookstores.
Says a lot, doesn’t it?
Gunpowder. It’s the smell of freedom.
Wow, I have no sense of smell and it constantly amazes me what people like to smell - in my head if if doesn’t taste of something then it doesn’t smell - I’m always amused at “the smell of rain”…
Napalm in the morning (somebody has to say it)
play doh
colorforms
white out
fireworks
freshly washed babies (I think it’s that Baby Magic stuff)
baking bread
and mother of all smells- lilacs. Can’t beat those two weeks in late April when my lilacs are in bloom.
The aroma of walking into a Pizza restaurant.
When I was a little kid, I’d go with my Dad to pick up the pizzas, and always get that rush of pizza smell when we’d go in.
Now, decades later, I still enjoy picking up the pizzas, and I love taking my own two small kids along to get them. I hope that in future decades they also have fond memories of that scent.