Can USCIS ever come to our home to check whether our marriage is real?

It can happen, but it is not a routine step in every marriage green card case. USCIS investigators may conduct a home or site visit when the agency believes additional verification is needed. If officers contact you, verify who they are, answer truthfully, and do not guess. A case that has reached an investigative stage should be taken seriously, especially if USCIS is trying to resolve inconsistencies in the record. If a visit happens, answer from what you actually know instead of guessing.