I recommend reading "Your Broke because you want to be", then follow that up with "The Millionaire Next Door" and then "Rich Dad Poor Dad". 

Adding a single ADU in southern CA is typically a poor investment.  

Purchase price: $179,000 Cash invested: $15,000 Lived in the property for 1 year.Knocked down living room wall, replaced Hvac, floors and gutted and remodeled the kitchen, attic insulation, converted the living room and the dining area into rooms.

The only people that are potentially bothered are the busy business executive type or, generally, people who are time poor but I don't think that's gonna be your clientele anyway.2.

Quote from @Luis Ramos: As a M.D. and Real Estate investor, I can attest that these poor business decisions come down to amount of schooling we have had.

If you haven't read Rich Dad, Poor Dad, read it asap.

Typically it is asking too much for rent, but it could be your advertising is poor or your property is not in good condition for that area."

Yes, you read that right, the American system was designed to best facilitate FAILURE not success. because when there is freedom to FAIL, it comes from consumers ability to choose, choose who is worth it, who isnt, and the poor performers fail and the good performers are rewarded. 

If you’re completely new to real estate, Rich Dad Poor Dad by Robert Kiyosaki is a great introduction to real estate investing.

That is a harsh reality every wholesaler has to face sooner or later.. well when you buy a property for 26k and you flip it for 75k real quick.. some seller just got ripped off big time and the wholesaler basically had to fib to the seller that they were paying market.. your basically stealing some poor sellers equity.. bottom line..