I think that a person with an allergy might even check the house for mold from time to time, because you are right, we may not see many hotbeds of mold. I had such a situation when the mold was in the upholstery of furniture and in carpets. I turned to a company providing services at https://www.kellercarpetcleaningtx.com/mold-testing.asp. They quickly and efficiently removed the mold in my house.