House with unapproved addition on MLS?

[Bienes Raices]

I heard that if a house is listed in the county appraiser website as a 2/1 (for example), but someone did an unpermitted "garage to a bedroom" conversion to make it a 3/1, that when you eventually sell the house the agent is required to still list it on the MLS as a 2/1. Is this true, and if so, do you steer away from these types of houses, or is it a non-issue? Thanks.