If the property does not provide for all three, you should not underwrite or make investment decisions based on the property operating as an STR. 

Based on what you are saying, the revenue on the property would be around $4,400 a month with a purchase price of $600K.

I did some research and my best guess is the automated messages are being sent to phone numbers based on data from data broker websites. 

Nick, consider contacting @Amanda Han, she is based in SoCal, an expert in the field and active member of BiggerPockets community.

I've wholesaled 30+ deals in Texas, even though I'm based in Southern California. 

Accuracy is harder to gauge, since you don't know if someone doesn't pick up whether it's a bad number, or just someone who didn't answer your call.I'm going to try Mojo skiptracing and see how they match up. 

This is a seller whose asking price is based on something other than market value – such as I want to sell and retire with a million (now 5 million) dollars.

I'm both a realtor & investor from the greater Los Angeles area but based in San Diego, looking to take off with my first deal.

The entire return is based on an unknown.  

Exactly how much the lenders will lend is based on the data on the property's marketability and the borrower's credit score.