Do you mean liquid or exhaust? Cause I’ll back you up on one of them.
The smell of a newly vacuumed room, dust and ozone, I suppose.
The smell from the inside of a tent - hot plastic, grass, rainwater and mould. Very evocative.
I love the smell of horses - manure, leather, sweat, hay, horse breath, hoof oil, it’s a really warm and happy smell.
The smell from an Irish pub - cigarette smoke, wood, Guinness, wet tweed, peat smoke and hot whiskeys.
The coppery smell the air gets right before a lightning_storm/rain.
The whiff of lighterfluid when someone lights a cigg with a Zippo lighter.
The smell of a good fishmonger’s.
The smell of dried cuttlefish. Just a tiny baggie is powerful enough to stink up a huge office space.
I also love the smell Diesel. Both the liquid and the exaust, and I love the smell of the river when it floods.
skunk
bus exhaust
turpentine
The scent of driftwood.
The scent of a well-oiled, broken-in baseball glove. Recalls boyhood pick-up games in the summer.
New magazines. Mmmmm. Newspapers are good too.
The smell of rain, especially when carried on a warm breeze.
sniff Ahh!
Diesel exhaust, but not gas. Nothing like walking downwind of a construction site when they’re firing up that bulldozer.
Skunk
Gasoline
Rubbing alcohol
Sulpher
Old books
Wet asphalt, again
Steel, or almost any metallic smell
Freshly baled hay (reminds me of playing in the barn on Grandpa and Grandma’s farm as a child).
fresh-cut wet grass.
The smell of the wood in the lumberyard.
The sweet smell of a grain elevator.
Mom’s lasagna.
Wow. I thought I was weird until I read the posts to this thread.
I worked in an auto body shop during the '70s and respiratory protection wasn’t widely used then. That’s probably where I came to enjoy the aroma of many nasty things like:
lacquer thinner
enamel reducer
methyl ethyl ketone
acetone
cutting oil when metal is being machined
Beyond that, the more acceptable scents I favor are:
kittens
my grandmother’s house (a memory scent)
lilacs
honeysuckle
I love the smell of a basement, but my favorite scent of all time is that of New Book.
Sharpie markers
Nail polish
Rubbing alcohol
The way your hair smells after you come home from a really hot, smoky concert.
But the best smell in the whole, wide world (IMHO) is brand new plastic- especially the kind that inflatable toys are made of.
Jiffy markers. Not Sharpies, but the original Jiffies. Heaven in a tube.
Old Xerox mimeograph copies. Purple heaven.
Leaded gas - the gas fumes and the exhaust it made. Unleaded gas smells terrible.
Grapefruit - especially at Safeway in the produce section, where it wafts spicy in the air.
Tomato plants.
Baby aspirins and/or new work gloves that smell like baby aspirins.
The ozoney smell of the air coming from the west just before a chinook blows into town in the middle of winter. The smell of rain on the air just before it starts pouring.
Oh, I forgot to mention for all you skunk-lovers that Indians believe that skunk smell helps with respiratory problems. So keep inhaling away :D.
Bounce dryer sheets
New plastic
Newly fallen snow (it has a smell, dammit!)
Pastrami
Ben Gay
I second Youth Dew, my grandma wore it and I still love the smell. I have her jewelry box that if I open it right, still sends a little waft out.
Machine shops and auto repair shops. Not the new ones, but the older ones, full of grease.
Cat fur. Much to my cats dismay, I love burying my nose in their fur.
Cedar closets.
Old money.
Mud. (okay, I also like the texture)
Mimeograph ink. (an auditory fav is the CaChunkCaChunk of the machine 
)
I’ve been discribed as a human bloodhound. I sniff EVERYTHING.
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The patch of fur directly behind a cat’s ear…mmmm…heavenly!
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My own um… bits after a shower.
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Permanent marker pens
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My kneecaps after I’ve sat out in the sun for a bit
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My pillow - it has a mixture of smells from my hair, to my perfume, to cigarette smoke. It all comes together to make a yummy sniffing experience when I go to bed