simplest aromatic ketone, in small amounts can be found in apple, apricots, cheese, chicory, banana, beef, and cauliflower. It is a precursor to useful resins and fragrances, is used in chewing gum and is an  ingredient in fragrances that resemble smell of almond, cherry, honeysuckle, jasmine, and strawberry. 
In humans, acetophenone is metabolized to benzoic acid, carbonic acid, and acetone, but it can be also excreted in its original form in feces and saliva.
Deuterated acetophenone smells fruitier than ordinary acetophenone. It also smells slightly of bitter almonds, just like many compounds containing the cyanide or nitrile group (C≡N) - as both C–D and C≡N bonds vibrate at the same frequency (about 2200 cm-1).   See also 2-aminoacetophenone

smells associated with sour and acidic substances such as vinegar, fermenting milk or vegetables, wine or lemon. Can be pungent and sharp as Formic acid and Capric acid in goats’ milk, vinegary as acetic and propionic acid, or sourish and cheesy as isovaleric acid responsible for "locker room" odor, "dirty socks" smell and stinky feet. Some acidic breath or body odors are associated with  yeast infections, cystic fibrosis and cancers, but it could also be a side effect of diet, medications and microbial imbalance (skin and gut flora)

Strong, acrid, pungent odor easily recognizable in cleaning products like Windex, vinegar, cat urine, chicken manure and, for some people, sweat. Gaseous amines possess a characteristic ammonia smell, liquid amines have a distinctive "fishy" smell. 
Human breath may have an ammonia-like odor (also described as urine-like or "fishy") in people with chronic kidney failure, uremia and other stages of renal disease. It occurs due to nitrogen-containing compounds, namely amines dimethylamine (DMA) and trimethylamine (TMA). Disturbances in the metabolism of amines may be also observed in epilepsy (increased 3-methoxy-4-hydroxyphenylglycol in urine), Parkinson's and dementia (deficient turnover of amines in the brain). Ammonia-smelling urine could mean dehydration or bacterial infection. 

Bad breath, fetor oris or halitosis is a symptom when a noticeably unpleasant odors are exhaled in respiration. Types of odors depend on the food eaten (such as garlic, onions, meat, fish, and cheese), hydration, body mass, smoking, alcohol consumption and other exposures. Low calorie dieting leads to acetone-like odors. Diseases associated with unpleasant breath include liver (fishy), kidney failure (ammonia-like), cystic fibrosis (acidic). Aging breath could produce cardboard-like smell resembling stale beer. 
About 20% of the general population are reported to suffer from foul-smelling breath to some degree. 5‑72% of people feeling that they have bad breath, have no genuine halitosis. 90% of those who is diagnosed with halitosis have it because of their oral bacteria below the gum-line and on the back of the tongue. The remaining 10% is accounted for by many conditions, including disorders in the nasal cavity, tonsil stones, sinuses, throat, lungs, esophagus, stomach, pancreatic insufficiency, food sensitivities or metabolic disorders like TMAU. 

The unpleasant smell of human body usually associated with stale perspiration.
Many organic and inorganic substances, byproducts of human and microbial metabolism, are released in the person's sweat, breath, urine and other fluids and gases, giving off a strong smell. Odors could be caused by disease (for example, diabetes leads to sweetish odor; kidney: ammonia-like; TMAU: dead-fish, urine-like or fecal; liver: sweet, mousy and fishy odors), infection (e.g., blue-green pus caused by Pseudomonas aeruginosa: grape-like; TB: tar-like; Scrofula: stale beer, yellow fever: butcher's shop), metabolic disorders or temporary problems (issues in cholesterol metabolism: rubber-like; menstrual period: tinny), imbalance or overgrowth of gut microbiota, hormonal imbalance, allergies, diet and medications, prior exposures to strong smells or poor hygiene. 
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See also Aurametrix summaries for Acidic smell; Ammoniacal odor; Bad breath; Burning smell; Chemical odor; Fatty odor; Fecal odor; Fishy smell; Foot odor; Musty odor; Old book smell; Rancid butter odor; Salty odor; Sulfur odor; Sweetish odor; Vaginal odor; Wet dog odor. 

Smoky smell resembling burnt substances.
Burning smell could be an olfactory hallucination or a real smell indicating a problem in the environment or human body. 
Could be a part of olfactory aura and the most common smell reported before a migraine episode (putrid smoky odors or scent resembling smoke, burnt plastic, burning wood, burnt toast or cigarette smoke). Other less common smells include toxic-smelling aromas, sewer-like stenches and decomposed garbage.
Chemical substances associated with burning smells include sulfur dioxide and volatile hydrocarbons.
The smoky odor character is most consistently associated with hydroxy and methoxy indanones and partially with methyl and methoxy phenols. Burnt odors are associated with furans and alkyl benzaldehydes. The oxidized oily character is usually ascribed to alkenones, dienones, hydroxy cyclocarbonyls, and indanones. Irritation factors seem most frequently to be associated with the lower molecular weight phenols. Some benzeldehydes and methoxy benzenes may also contribute to this sensation. While some unsaturated aldehydes contribute to a portion of the exhaust odor complex, the most abundant exhaust aldehydes do not appear to contribute significantly. Neither sulfur nor nitrogen containing species contribute to the smoky-burnt odor complex and exhaust odors.

Ethyne, ethene and benzene were found to make up well over 80% of the non-methane hydrocarbons for efficient flame combustion of wood. The proportions for low-temperature smouldering are similar to those of environmental tobacco smoke. The hydrocarbons from wood burning differ from those in traffic-polluted urban air by higher proportions of ethene and alkadienes and lower proportions of alkanes and alkylbenzenes which are emitted as unburnt petrol components. Ethyne may be a suitable tracer hydrocarbon for emissions from efficient wood-burning installations. The high proportions of the genotoxic hydrocarbons ethene, propene, 1,3-butadiene and benzene are of concern with respect to health hazards​

Rotting-flesh sickly-sweet smelling compound produced from amino acid lysine by microbes such as E. coli, Shewanella putrefaciens, Vibrio spp., and Morganella morganii.  Also known as  1,5-pentanediamine and pentamethylenediamine. 
Cadaverine is one of the best-characterized chemicals responsible for the "smell of death" (from decomposing, putrefying body) repelling most animals. Cadaverine levels are also associated with oral malodor, independently of the level of Volatile Sulfur Compounds.

plastic-like odor or smells like industrial strength cleaner, bathroom cleaner, kitchen cleaner, sulfurous and medicinal. 
Examples of compounds with chemical odor are methyl-p-xylene, (Z)-2-penten-1-ol  and fucoserratene  that smell like plastic, methanethiol and dimethyl sulfide - that could smell like gasoline. Isoprene in breath associated with problems in cholesterol metabolism could smell like new rubber tubing.