You have a very valid question. The answer is not as simple as circling areas on a La Jolla map. Soils engineers and "geo tests" are common enough to real estate transactions in La Jolla that seasoned agents should be able to guide and advise you.
There have been some well-publicized areas of hillside slipping; and several other areas where land or construction limitations are known by area agents and residents. If you have any doubt, get a "geo test" for peace of mind.
Soils tests are crucial to evaluating properties in this area, and an experienced agent will have seen testing results and will have discussed soils hundreds of times-- he or she be able to help you discern areas of concern, and will advise you of the best engineers to undertake this work.
When I built my home 7 years ago (in La Jolla) we reinforced with steel beams to prevent this type of issue. I would advise a home of newer construction (less then 8 years old) that has reinforced steel beams if it has a significant slope.
The homes that I have sold over the years that have had soil issues were due to A: homeowner negligence (water issues) & B: poor quality fill soil (which again essentially is a water issue because the fill soil used absorbed water poorly).