Sometimes you shouldn't "tell" at all. Hemingway and Elmore Leonard want their protagonists to be "manly" and not show external feelings, so they use little telly language.

Here's a different but common reason not to tell. This is a long passage from The Heart is a Lonely Hunter, end of part 2, with lots of body language and almost no "telling" at all. After it, I'll give my opinion on why that is. (You don't need to read the spoiler at the end.)

I have to qualify that in two ways. First, there is telling. John Singer complains "furiously" and is "beside himself" when the slot machine doesn't work. The humidity oppresses him, and he has a headache. But these things are indirect. He isn't furious because of the slot machine, or because of the heat, and you need to figure out why he has a headache. This is similar to what Mystic calls "Implication outside the initial scope." You need to figure out what deeper feeling caused these feelings.

Second, there's a continuum from telling to showing. Categorizing things into "showing" and "telling" is a simplification. Maybe I'll post on that later, with examples.

And, yeah, she uses "listlessly" too often.

I changed the "telly" speech tag from maroon to brown, so you can distinguish it from adverbs, which in this passage are not very telly. Key:

red = adverb

brown = "telly" language

yellow = sensory language that describes Singer's feelings in a non-telly way

green = simile or metaphor

blue = an adjective, adverb, or verb that isn't literally correct (metaphorical)

lavender = body language

At the asylum he sought Antonapoulos first in the sick ward where he had been confined before. But at the doorway of the room he saw immediately that his friend was not there. Next he found his way through the corridors to the office where he had been taken the time before. He had his question already written on one of the cards he carried about with him. The person behind the desk was not the same as the one who had been there before. He was a young man, almost a boy, with a half-formed, immature face and a lank mop of hair. Singer handed him the card and stood quietly, his arms heaped with packages, his weight resting on his heels.

The young man shook his head. He leaned over the desk and scribbled loosely on a pad of paper. Singer read what he had written and the spots of color drained from his cheekbones instantly. He looked at the note a long time, his eyes cut sideways and his head bowed. For it was written there that Antonapoulos was dead.

On the way back to the hotel he was careful not to crush the fruit he had brought with him. He took the packages up to his room and then wandered down to the lobby. Behind a potted palm tree there was a slot machine. He inserted a nickel but when he tried to pull the lever he found that the machine was jammed. Over this incident he made a great to-do. He cornered the clerk and furiously demonstrated what had happened. His face was deathly pale and he was so beside himself that tears rolled down the ridges of his nose. He flailed his hands and even stamped once with his long, narrow, elegantly shoed foot on the plush carpet. Nor was he satisfied when his coin was refunded, but insisted on checking out immediately. He packed his bag and was obliged to work energetically to make it close again. For in addition to the articles he had brought with him he carried away three towels, two cakes of soap, a pen and a bottle of ink, a roll of toilet paper, and a Holy Bible. He paid his bill and walked to the railway station to put his belongings in custody. The train did not leave until nine in the evening and he had the empty afternoon before him.

This town was smaller than the one in which he lived. The business streets intersected to form the shape of a cross. The stores had a countrified look; there were harnesses and sacks of feed in half of the display windows. Singer walked listlessly along the sidewalks. His throat felt swollen and he wanted to swallow but was unable to do so. To relieve this strangled feeling he bought a drink in one of the drugstores.

He idled in the barber shop and purchased a few trifles at the ten-cent store. He looked no one full in the face and his head drooped down to one side like a sick animal’s.

The afternoon was almost ended when a strange thing happened to Singer. He had been walking slowly and irregularly along the curb of the street. The sky was overcast and the air humid. Singer did not raise his head, but as he passed the town pool room he caught a sidewise glance of something that disturbed him. He passed the pool room and then stopped in the middle of the street. Listlessly he retraced his steps and stood before the open door of the place. There were three mutes inside and they were talking with their hands together. All three of them were coatless. They wore bowler hats and bright ties. Each of them held a glass of beer in his left hand. There was a certain brotherly resemblance between them.

Singer went inside. For a moment he had trouble taking his hand from his pocket. Then clumsily he formed a word of greeting. He was clapped on the shoulder. A cold drink was ordered. They surrounded him and the fingers of their hands shot out like pistons as they questioned him.

He told his own name and the name of the town where he lived. After that he could think of nothing else to tell about himself. He asked if they knew Spiros Antonapoulos. They did not know him. Singer stood with his hands dangling loose.

His head was still inclined to one side and his glance was oblique. He was so listless and cold that the three mutes in the bowler hats looked at him queerly. After a while they left him out of their conversation. And when they had paid for the rounds of beers and were ready to depart they did not suggest that he join them.

Although Singer had been adrift on the streets for half a day he almost missed his train. It was not clear to him how this happened or how he had spent the hours before. He reached the station two minutes before the train pulled out, and barely had time to drag his luggage aboard and find a seat. The car he chose was almost empty. When he was settled he opened the crate of strawberries and picked them over with finicky care.

The berries were of a giant size, large as walnuts and in full-blown ripeness. The green leaves at the top of the rich-colored fruit were like tiny bouquets. Singer put a berry in his mouth and though the juice had a lush, wild sweetness there was already a subtle flavor of decay. He ate until his palate was dulled by the taste and then rewrapped the crate and placed it on the rack above him. At midnight he drew the window-shade and lay down on the seat. He was curled in a ball, his coat pulled over his face and head. In this position he lay in a stupor of half-sleep for about twelve hours. The conductor had to shake him when they arrived.

Singer left his luggage in the middle of the station floor. Then he walked to the shop. He greeted the jeweler for whom he worked with a listless turn of his head. When he went out again there was something heavy in his pocket For a while he rambled with bent head along the streets. But the unrefracted brilliance of the sun, the humid heat, oppressed him. He returned to his room with swollen eyes and an aching head. After resting he drank a glass of iced coffee and smoked a cigarette. Then when he had washed the ash tray and the glass he brought out a pistol from his pocket and put a bullet in his chest.

(I marked "wild sweetness" as non-literal because wild strawberries are not sweet at all, so presumably the author is trying to convey something else with that word.)

The author (Carson McCullers, a mere 23 years old when she wrote this) doesn't tell us how Singer feels because Singer doesn't know how he feels. Exploring feelings that we don't understand and can't name is one of the main purposes of literature. One mark of great fiction is showing characters have feelings that there are no words for. You can describe it with words, but not with a single word; I recall a line from my annotation of The Last Unicorn: "She stood very still, neither weeping nor laughing, for her joy was too great for her body to understand." For this, you need to show rather than tell. So great stories are likely to have sections that show but don't tell. Causation doesn't run the other way, though: Showing but not telling doesn't make something great.