No, not likely dismiss. If the room is illegal, then under the case of Gruzen v. Henry (1978) 84 Cal.App.3d 515, the landlord is not entitled to collect or request any rent. California law does not reward a landlord who has an illegal structure, and punishes the landlord by declaring the contract leasing that structure "void."
Typically, a landlord trying to evict a tenant from an illegal rental would get "restitution" of the premises (an order that the tenant be removed from the illegal structure without owing rent) but not any money damages in an unlawful detainer judgment. The legal basis for such ruling is that the courts will not enforce any illegal contract.
So basically, the landlord will still be able to evict you from illegal rental dwelling based upon a 3-day notice to pay or quit, but the landlord might not be entitled to recover a money judgment for unpaid rent.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice for a particular case. This Avvo.com posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, please consult with your own attorney.