「Selling services with emerging shafts」is associated with DIFFICULTY SWALLOWING, with the reasons being intuitively obvious…「pseudo-grains」in Chinese are 'false seeds,' a euphemism for gonorrhea. When betrayed by man's best friend and bitten: MAD-DOG WEED (note: not a species of cannabis), an herb used to treat rabies, also purported to keep fairies, imps, and leprechauns at bay (well, do you see any? it must be working then).
　Association with rabies with「emerging shaft with sales and services of penis-fleshpot orifice copulation」is likely due to the whitish foaming around the mouth of an animal infected with rabies, and the whitish foaming around the mouth of a very busy service provider, DIFFICULTY SWALLOWING:
　「Hydrophobia ('fear of water') is the historic name for rabies. It refers to a set of symptoms in the later stages of an infection in which the person has difficulty swallowing, shows panic when presented with liquids to drink, and cannot quench his or her thirst. Any mammals infected with the virus may demonstrate hydrophobia. Saliva production is greatly increased, and attempts to drink, or even the intention or suggestion of drinking, may cause excruciatingly painful spasms of the muscles in the throat and larynx. This can be attributed to the fact that the virus multiplies and assimilates in the salivary glands of the infected animal for the purpose of further transmission through biting, and the infected animal's ability to transmit the virus will reduce significantly if [she/he] can swallow [her/his] saliva with/without external source of water.」
　　[　https://en.wikipedia.org/wiki/Rabies 2015-03-03　]　
　Furthermore, associating rabies with emerging shafts and trading with service providers could be due to the fact that visiting brothels staffed with highly-trained, life-long sex slaves proficient from a very young age may cause some of the same effects as rabies…compare this description of rabies to an escort addiction:「There may be also discomfort or a prickling or itching sensation at the site…, progressing within days to symptoms of cerebral dysfunction, anxiety, confusion, agitation. As the disease progresses, the person may experience delirium, abnormal behavior, hallucinations, and insomnia. The acute period of disease typically ends after 2 to 10 days. Once clinical signs…appear, the disease is nearly always fatal, and treatment is typically [only] supportive. …Once a person begins to exhibit signs of the disease, survival is rare. To date less than 10 documented cases of human survival from clinical rabies have been reported…」
　　[　https://www.cdc.gov/rabies/symptoms/index.html 2015-03-03　]　 that's ten cases in the entire history of record-keeping of the disease, estimated by the World Health Organization to cause at least 55,000 deaths per year in Asia and Africa.
　　[　https://www.ohsu.in/one-health/ 2023-05-17] (those are not good odds).

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: Alisma plantago
Unihan extended: water plant
EDRDG: water plant