Zeng entered politics in 1991, when he became a Workers' Party member; thereafter he renounced his affiliation to the group and became a perennial candidate in Singaporean elections, albeit always dropping out of contention at the last minute.

Zeng was also an active acupuncturist who arranged for global meetings and operated an acupuncture centre in Singapore, later changing his focus to selling healthcare products after a string of molestation lawsuits initiated by his patients.

Zeng was diagnosed with terminal cancer in 2014; this necessitated the excision of his entire nose, which led to significant facial disfigurement, and he became a tissue paper peddler, abandoning his previous jobs.

[20] In a 1996 lawsuit he was involved in, Zeng stated that he contested the 1991 general election only to gain publicity for his acupuncture business.

Zeng alleged that he was informed that he could not contest because of an offence he had incurred four years ago – scolding two police officers with vulgarities, to which he argued it was his bird that committed the deed.

He also explained that he wanted to give in to candidates of higher caliber than him, adding that "fools rush in where angels fear to tread".

[25] In August 2015, he declared that he would be contesting the Potong Pasir Single Member Constituency, pledging to "fight until the end",[26] but after less than a week he changed his mind, citing his being the only independent running,[27] his good ties with Chiam See Tong, and not wanting his participation to cause a three-cornered-contest as reasons for his withdrawal.

[33][c] After Zeng published controversial and self-admittedly "misleading" advertisements of it in 1991,[35][36] the 28th World Congress of Acupuncture and Complementary Medicine, which was supposed to have taken place in Singapore, changed its host country to the Republic of China.

[6] It moved to Toa Payoh and its sole basis of operations became selling healthcare products, including slimming oil[15] and a "hair regrowth shampoo" made of vegetable and chocolate.

[48] Singaporean comedian and blogger Lee Kin Mun, better known as mrbrown, portrayed Zeng in a satirical video on the 2013 Punggol East by-election.

[49] Zeng is notable for his unorthodox,[47] Arab-style[45] clothing, often appearing in his "signature" thawb, accompanied by either a red-and-white keffiyeh[47][50] or a golden scarf.

[58] In December 1991, Zeng was involved in an accident while on his leisure craft Yeeyew, which he had purchased for $80,000 as a tin jubilee gift for his wife.

[23][24] Whilst the trial of Kong Hee was underway, Zeng endorsed him as a "good preacher" capable of "bring(ing) people to the Lord", adding that he was a Christian who had donated large amounts of money to City Harvest and attended many church sessions.

[71]In a 2017 interview, Zeng identified himself as both a Muslim and a Jehovah's Witness, and described the unfortunate happenings in his life as divine salvation.

[10] In March 1988, a clerk filed a lawsuit against Zeng, attesting that he had "kissed her and touched her breast in his clinic" during a hair-loss and weight-gain treatment session in November 1986.

[1] Zeng countered that the accuser was merely making use of him to get her "jealous" boyfriend's attention,[1] labelling the case as an "extortion bid".

[73] In December 1991, the owner of a white Mercedes-Benz limousine lodged a complaint against Zeng for not having paid for his vehicle, which he rented in November of that year, during the General Election.

[80] During the trial, Zeng refused to settle in court, repeatedly stating that he was a "knight of Saint John"; the claim was found to be untrue.

[90] During that period in jail, Zeng alleged that he was stripped of some of his basic rights; he claimed that as a result of being denied access to clean bathing water, he had developed painful rashes near his rectum.

[80] He added that the police in charge of him called him crazy and wanted to "put him in a psychiatric cell",[80] and also accused them of forcing him to confess through physical means.

[92] In around October 2009, a lawsuit was filed against Zeng for placing at his two stores banners of escaped terrorist Mas Selamat bin Kastari – which he argued were merely sunshades – without official permit.

[96] In October 2018, former police officer Seah Chin Peng was charged in a district court for deliberately damaging Zeng's walking stick two years ago and attempting to suppress the truth behind its destruction.