In Rancho Bernardo I suspect it is not worth the risk as their is high chance the illegal unit will get tagged.Best choice is to purchase properties that already have legal ADU.  

@Gary ReynoldsI suspected as much.

Biggerpockets has several horror stories and I suspect most of us know more.

I suspect saving it will not result in much savings over a new build.  

But if you prime, paint and topcoat I suspect the labor is equivalent to floating a vinyl plank over the top.

They moved out and ended up renting separate houses due to changes in their personal circumstances (boyfriends, etc.)I suspect the folks from SmartAsset also don’t take into account people who sell their home and have cash for a larger DP to reduce the amount of money they have to borrow, ie, to reduce the reliance on the size of their income in relation to price they are paying.

As you know it gets pretty dead up there during the winter so I suspect the income from any vacation rental would be very seasonal as well.

I suspect Mr Big Cheese would quickly drop his moralizing.

When people get only texts or a form, it can seem suspect because that's how scammers operate.

Your time is valuable- if you need to hold for 5 years, as you suspect, well then you'd better be finely compensated for your time(and trust me, there's time involved) and for locking up your capital.