In Del Mar it would not make much difference at all sale or price wise. It can not legally be considered in the Sq-Ft calc of the house, but the price/sq-ft is a joke in Del Mar anyway.

If they ever did any construction/remodeling on the property that required permits and inspections, they could get in a sticky situation. The Inspector could cite and force them to bring it to code if it is habitable, i.e. obviously a granny flat, and not storage shed or garage, if it was never permitted and inspected when it was built. Read city income from more inspections and permits?!? That could be big $$$$ if it was originally built by inbred jed and the country quire swinging left handed hammers. Or they would make you tear it down if you don’t want to bring it to code. I have seen this scenario play out several times, although not in Del Mar specifically.

Speaking of permits in Del Mar, you need to get approval from the design review board. The DRB in Del Mar is a bunch of worthless bitter geriatrics. My partner has had to sue Del Mar several times to get anything done there. Once had to sue to the actual 2 DRB members personally that would not approve the project but would not give any reasons. Bend over backwards, do everything they want, be in full compliance, and then they still won’t approve your project because it “just doesn’t *FEEL* right for Del Mar”. Del Mar is the WORST area for the “I have mine – now lock the door” syndrome.