Because that is what it smells like, if it gets dirty. If your girl is clean her cooch'll smell clean. One girl I dated, her pussy smelled delicious. Part of that was just how attracted to her I was though. Another, it smelled like someone's armpit, even fresh washed.
Meanwhile (do not read if you have a sensitive stomach or are eating) [spoiler]I dated a girl from Australia for two years. I've posted this story hundreds of times, it's actually how I lost my virginity. She used to be morbidly obese, lke over 300 pounds. When we met she was down to like 140. Looked good covered up, a nightmare naked. Anyway the massive weight loss fucked up her hormones. Of course, she confided in me she always smelled bad, that girls complained of how she smelled at sleepovers. Bad BO, bad breath, the works. Her pussy though, her pussy was a thing of cosmic horror. You know that story The Colour out of Space? Okay, that, but instead of a tangible color it was a solid mass wafting out of her cunt. I tried suggesting she clean it gently. "It's self-cleaning" she'd say "It'll mess up my PH balance if I use soap". One time I pretended I wanted to fool around in the shower with a bar of dial soap. She came, sure, but I just wanted her cunt to stop stinking.
So what exactly did it smell like? What was so bad I couldn't look directly at it, and even breathing through my mouth it still made my eyes water? If this description starts to sound familiar, you've read this story before.
Take a dirty old bathtub covered in grime. Okay, now take a bunch of aquariums filled with dirty water filled with the sort of fish that like to live in brown water, and dump all that in there, fish poop and multicolored rocks and all. Now go into an imaginary fridge that half works, reach into the back and dredge out two slimy, half-eaten sides of ham that have been sitting in there for two thanksgivings. Dump out a bunch of bologna that's been left out in the sun for a month in there as well. Now I want you to find a fish corpse, a big bloated one ants have started eating away on, you can see the skeleton. Take a rusty shovel, dig up the fish's corpse, and along with the dirt and the shovel, dump that in there as well. Now I want you to picture two nasty old rubbermaid trashcans FILLED with filthy pennies. Just pennies. You know the kind, they're all sticky and green and black. Just dump them right in there with everything else. Now to top it all off, I want you to imagine some nickelodeon Gak, you know the slimy stuff they sold in the 90's? Remember how gross it got after kids played with it for a while? Go down into an imaginary basement, dust off an imaginary box labeled simply GAK on the side. Tear open the top to find dozens of nasty, grimy ziploc bags filled with old Gak from the 90's. Into the mix it goes. Now put on your glove, reach in for the handle to the shovel, and mix everything up as fast as you can before your glove melts off. When your hand starts to burn drop the shovel and run to the sink.
Now I want you to go back to that tub, close your eyes and picture an axe wound, inhale deeply, stick out your tongue, and lean in for a mouthful.[/spoiler]
I practically started crying afterwards washing my hands and junk off in the sink. "What if it won't come off? What if I'm going to have to smell this forever? WHAT IF THEY ALL SMELL LIKE THIS AND I SIMPLY NEVER KNEW?!" but thankfully all experiences after that were pleasant.