Legal Question in Landlord & Tenant Law in California

You can file a motion to strike the answer. Typically, that box would not be checked in your situation because, as the complaint is verified, the defendant has to respond to each of the material facts stated in the complaint rather than to generally deny everything, without specifics.

The "law does not deal with trivial issues." So what that it was checked; it is something easily cured. If the defendant merely filed a general denial, that is another issue that the court would consider worth considering.

The court clerk is not permitted to pass judgment on whether an answer is adequate or not. They must accept filings that are in a proper form and not barred by a prior event (such as trying to file a default after an answer has already been filed). If the defendant checked that box and did not check and fill in the parts regarding what was admitted or denied, then the answer is defective, but it is not improper to accept it for filing. It is up to the plaintiff to bring the defect to the court's attention by way of demurrer or motion to strike asking the court to throw out the answer. Since the court would almost certainly grant the motion, but would also do so with leave to file an amended answer, all it would do to file such a motion would be to play into the tenant's hands by further delaying a trial and judgment of eviction.