The most likely scenario in most parts of the country, is Market saturation driving down rates.

I live in Southern California where the market is extremely saturated, prices are high, and cash flow is extremely difficult.

It's merely aggregated data.Response lists are those who have previously responded to your marketing or that of another marketer's.You're attempting to do lead generation in what may be a saturate market.

It became a curiosity to me because in these other popular markets like CA and AZ, there saturated with competition.

David that is such a broad question.Shopping centers vary by age.Generally everything recycles after so many years.For instance if a shopping center is 40 or 50 years old it is past it's life cycle.Generally at that point you tear it down and build new.If a shopping center is say 20 years old many will just reface the outside to make it look new and repaint and re-stripe the parking lots.This is all predicated on if the shopping center still has a viable location or has growth shifted and now the center is int he old part of town.If it's in the old part of town refacing might not make sense and instead you buy at a lower basis to rent to Big Lots,outlet stores,etc. for less money.Still a tenant that will rent from you but at a lower cost because the area has shifted.With shopping centers it's all about the corner and access from 2 points,red lights,traffic volume and flow,etc.Anchored shopping center versus unanchored,tenant mix with credit rated tenant and frachise concepts versus mom and pop operations.Just like with houses you can run into big repairs with older shopping centers.Don't pay attention to current leases as much going in as what is market rent now and any leases fixing to reset.Also need to know level of shopping center saturation in a 2 mile radius depending and could be tighter or bigger in size depending on rural,subrurban,or urban core,and population count and demographic.Hope it helps.

Don't quit your job. especially when you are starting its good to have a solid W-2 to fall back on in times of capital stress and lenders want to see that. save save save. the most important aspect is buying that first property to catapult you into the REI world. sure you can wholesale or get a license to sell RE, but honestly I think the market is pretty saturated with these positions.

You should research the specific market, competition, potential over-saturation, what can help you stand out etc.Generating great Airbnb returns stems from having a unique property, marketing it well, and operating it efficiently.

What if Seattle got saturated with units and rents dropped.

I was looking closer the Metro North line but not sure if it's already too saturated. 

I think Dallas has become enough saturated that cash flows are almost impossible, and buying in the midwest of some parts of Florida has become the new norm.