I do not know about sweetness and aroma perception nor if they are related the way other tastes can be, but as Jim stated how taste is affected by diet (artificial and overly-sweetened beverages and some processed foods), the same can be applied to aromas. Use of colognes, perfumes, scented candles, room aroma dispersion devices, sprays, 'spring-fresh' fabric softeners and laundry aroma additives (Fabreeze is Satan's Deodorant), and other such things all can affect how aromas are perceived. And don't get me started on Cremora.

Randy G. wrote: ... (Fabreeze is Satan's Deodorant)

It's actually kind of genius: why bother masking smells if you can shut down people's sense of smell.

Febreze is a cyclodextrin, it's molecular structure forms a cavity that can capture other (suitable) molecules.

Some people have more taste buds that detect bitterness. I am one and there is no coffee or espresso served black anywhere that tastes sweet to me. Not even the tiniest bit. I like to say espresso tastes like hot pesticide. However, I really, really like the flavor of coffee with sugar and milk. So much so that I have a Niche and a Robot to make my one daily coffee beverage.

Also, if you have ever smoked tobacco your bitter taste buds have been suppressed and you don't taste bitter compounds effectively. That is why really bad coffee and cigs were consumed together in mass quantities for so many decades.

So is there such a thing sweet espresso? Sure for some people, but for something like 20% of the population, no way.
The OP should consider that sweet espresso may never be a reality for them.

Welshdog wrote: Also, if you have ever smoked tobacco your bitter taste buds have been suppressed and you don't taste bitter compounds effectively. That is why really bad coffee and cigs were consumed together in mass quantities for so many decades.

This is fascinating. Do you have a reference to anything published on this matter?

BaristaMcBob wrote:Interesting topic. I've wondered this myself. I followed the links presented above. They lead to more discussion and more links, without any solid explanation at the end of the chain. After looking at all that, I've come to the following conclusion based on my own experience:

1. "Sweet" espresso means not bitter and not sour.
2. It means enjoyable without sugar.
3. It means being able to discern the subtle flavors
4. It does not mean sweet as in sugary sweet.

If this is so, then I suppose I could say I only drink sweet espresso. If a bean does not tick all those boxes, I lose patience and move on. In my experience, many traditional espresso blends tick those boxes (if properly extracted and not stale, of course). Maybe I have relatively few or deficient bitterness receptors, as I don't have a problem with dark roasts... though it must be said that any bean or blend can be ruined by an incompetent barista.

But I have also experienced an entirely different kind of sweetness in espresso. This was a single origin Ethiopian, roasted medium-ish. It literally felt like drinking a mango. Very enjoyable, and definitely sweet, just very different from the sweetness I associate with darker, more traditional espresso.

mathof wrote:This is fascinating. Do you have a reference to anything published on this matter?

I was also curious about this and did a quick search. There was a paper published in 2014 that looked at 309 non-smokers, 94 current smokers, and 48 former smokers and found that bitter taste recognition failures occurred more frequently in the latter two groups (19.8% and 26.5% vs. 13.4% for non-smokers).

Given that nicotine is a bitter tasting substance I couldn't help but wonder if smokers as a group start out differently. Indeed, there is evidence that genetically based sensitivity to bitter taste is less common in smokers. So, as with many things, it's hard to unwind it all.

Burnt toast. You forgot to include it in the morning ritual. My dad used to do that: percolator coffee, black toast, and a cigarette.

mathof wrote:This is fascinating. Do you have a reference to anything published on this matter?

https://www.medicalnewstoday.com/articles/274698

Also lots of info on "supertasters", people with more than the average number of taste buds. Supertasters have trouble enjoying black coffee, brown liquors, broccoli, brussel sprouts, asparagus and sometimes even chocolate. I cant tolerate black coffee of any kind, asparagus or most any brown liquor unless it is in a mixed drink. That being said, milk and sugar make coffee wonderful for me. I eat chocolate by the pound and do enjoy broccoli, so like everything else regarding human biology, there are a lot of variables.

https://en.wikipedia.org/wiki/Supertaster

Welshdog wrote:https://www.medicalnewstoday.com/articles/274698

That's an article about the same paper I found. It apparently received a lot of press at the time.

Welshdog wrote:I... do enjoy broccoli...

But does it taste sweet to you?

Marcelnl wrote:Febreze is a cyclodextrin, it's molecular structure forms a cavity that can capture other (suitable) molecules.

To me, it's like the smell equivalent of being blindfolded. Do you put a paper bag over your head if a place looks bad? I suppose if you've been miseducuted into not using smell for information about the world, but simply for "avoid that," these deodorizing concoctions have some kind of value. Part of the value of getting into coffee is that it can reawaken the sense of smell.