There's your prompt, sir - see Chris M.'s freebie for gum brands at:
"A factory, riddled with paranormal activity, and it still makes/once made a popular brand of chewing gum"
It's going to need vats, and big paddles in giant mixers, and maybe it's automated or there are workers that do it artisanal style
It doesn't need to be haunted, I guess. Infested? occupied? one of those might suit you better.
Also, there should be a way to work in a catchy jingle and some competing brands of awful but rare (and thus prized) candy or candy bars and gum
To preempt the most obvious monster:
"The Gum Wraith
In the year 189X, before this country's fixation on The Fine Arts of the Springy Chaw, only a few small Gum Guilds existed, and they mainly served the wealthy in Bastion's Upper Crust. The owner of Horace's Hoary Horehound brand (one Flernt McTrode, Esq.) was known to use whatever herbal ingredients were at hand in his special proprietary blend of "27 Secret Herbs and Spices" sometimes varying the recipe by as much as 15 ingredients more or less - usually less. In the autumn of that year, during a particularly harsh economic downturn coinciding nicely with a drought, Mssr. McTrode purchased in haste and error a brick of wormwood harvested in the light of the moon in a potter's field. For the shillings he saved (which he and his wife quibbled over incessantly and that drove her to cuckold him) he let loose a minor catastrophe. Beginning with the disappearance of his wife, there followed in the district a great number of vanishings, of people of all rank and station. All were creditors to McTrode, and some had romantic linkages to his wife and her sister - McTrode patiently explained to the press that Mdm McTrode was on a fur-buying expedition on the continent and would be back when the fashion season commenced again.
When the truth was revealed - his animosity and pent up embarrassment managed to animate whole vats of chicle mixed with his latest blend - McTrode was tarred and feathered and the Triple H brand was liquidated and the proceeds sold to the widows of the district. Madame McTrode returned from her vacation to find herself a pauper and her husband a fugitive from Bastion. He is reported to have travelled the country advising other learned craftsmen, and was influential in rise of the Chewing Gum Craze of the 1920's.
a Gum Wraith is an animate and dimly aware mass of fermented Chewing Gum, animated by spite or other strong emotions. It attacks with Big Chomping Teeth for 1d6 per round, and on a Critical Hit it will swallow the character in question. Any successful melee hits upon it require a Dexterity save or else the attacker is stuck fast in the mass. a successful Strength saving throw will free him or her, but allies can pull him or free by sacrificing an action for a full round. Cold effects will do improved damage, and heat will do reduced damage and allow the Gum Wraith two attacks per round.
If swallowed, a PC is likely lost but permanent injuries may be sustained instead at the Judge's and players' discretion.