Now, I'm going to warn anyone ahead of time, this comes from conversations in meat space, not reading. So if you want sources, you'll have to go dig up a body, and hunt down an ENT that I can't even remember the name of.

With that disclaimer, the smell of boogers outside the nose is the smell of the proteins reacting with the acids on your fingers and the air.

When they're inside the nose, they're moister, and stuck to the inside of the nose, with no contact with anything volatile.

If you want to test this, get some plain, cheap tissues. For a few hours, blow your nose occasionally, sniffing the resulting expulsion. Notice that there will only be a very faint smell, if any.

Now, pick your nose and wipe the substance onto the tissue and wait a few seconds before sniffing. You should notice a slightly stronger smell. Then, just pick the nose and roll the booger around a little, then sniff. Slightly stronger again.

Boogers, inside the nose, are a lot of water, mixed with your own proteins and traces of whatever microbiota are there, plus hints of particulates. In other words, they're damp and warm, but non reactive in situ.

Once you pull them out, you're exposing a greater surface area to air, causing the water to evaporate faster, and anything I'm suspension to be exposed to air.

If that removal is done via bare finger, the oils and acids of your sebum can react with the proteins and other solids.

Happens with mucous from the lungs as well. Ever notice tar when you're sick and cough something into your hands, it smells different than when it's into a tissue? Not that most people would notice, what with being sick, and possibly also having a stuffed up nose.

But guess what! It isn't just those mucuses. Vaginal secretions change smell on fingers vs other surfaces. Not as much, because the ph involved is different, but if you've got a sensitive sniffer and pay attention, it's there. Even semen changes smell a little, though you really gotta pay attention because it's over fast for some reason I've never figured out.

In theory, I'd guess that rectal mucosa would too, but that's going to have much stronger smells to begin with because of where it's produced. So I doubt you'd be able to detect it even if you were willing to try. I'm not willing to try.

Fwiw, yes, I know that means I've sniffed my own semen on my fingers. What? You weren't curious about the stuff when you first cranked some out?

You're just smelling your finger. That's why it smells like shit.

Your lungs have a scent when you exhale air ... your brain filters out that smell ... your senses know its there, your brain just ignores it - it's all automatic

Same thing with the 'taste' of your mouth and saliva

Same thing with tinnitus ... everyone has it to a degree ... that little ringing in your hearing ... your brain just filters it out

You have a natural blind spot right in the middle of your vision, the edges of your vision is also uneven and you can only accurately focus on about 10% of your sight in front of you ... you brain just automatically makes you think that everything is in focus everywhere ... the edges are never in focus .. you move your sight to what you thought was edge, now its in the focused part and it makes you believe that everything was in focus the whole time ... your brain just manipulates all this to make you think you have a clear focused vision 180 degrees in front of you ... but really only about 10% is in focus and there is a black blind spot in the middle of it ... your brain also automatically fills in that black spot every time

We have imperfect senses ... our brain just plays tricks on us to make us think and believe that we have this awesome perfect sensory system ... it isn't perfect and it isn't as great as we think it is.

I suppose Anon is smelling all the voltatiles from the part of the booger that was touching the inside of their nose and therefore didn't dry out until they removed it.

Flashback to smelly sneezes if anyone remembers.

Taste it