FWIW – Zoning laws are one of the biggest issues that pertain to your question. You can go here:
http://apps3.sandiego.gov/siteinfoweb/begin.do
and enter the address of the home to determine the zone or zones in which it lies. Here are the rules relating to residential base zones, if you feel like looking through it: http://docs.sandiego.gov/municode/MuniCodeChapter13/Ch13Art01Division04.pdf

Basically, different rules apply to different zones; something that requires a special permit in one zone may not be a problem a block away.

I have to say I disagree with a lot of the people who have already replied. The value of your home is influenced by the zone in which it lies. When someone buys (or rents) a home, they are paying for and relying on the zoning laws that pertain to the area. I don’t know anything about this specific situation, but if the minidorm rules, zoning laws, CC&Rs or whatever prohibit multiple tenants – those are the rules and they should be followed IMHO.