What is a roundworm?

"House bug" is a self-employed person who specializes in buying and selling second-hand houses and takes "buying and selling houses to give others a price difference" as his occupation.

Their profit mainly lies in earning the difference, buying at a low price and selling at a high price.

They are "agents" but they don't charge agency fees. In order to steal money from buyers and sellers, they are not allowed to meet directly to discuss the price. It is also a competitor that makes formal intermediaries "headache".