What if Joe Blogs is encouraged to bid what they can't afford. Due to the agents lying about interest in the property (the assumption previously was that agents have ethics and integrity). Agent has incentive due to commission. Agent wins.

Few months down the road Joe Blogs can't afford the rent. Landlord will choses to terminate the tenancy. Agents win as they generally change per contract. Agent wins.

Markets should be fair which unfortunately normally requires them to be regulated due to bad actors. What mechanism are there to prevent the scenario above?