The closer we can get to the raw data, the better we can identify patterns, but Zillow, Trulia, Redfin, Homesnap, etc. all provide data.

But a pattern of going nuts at Christmas on a credit card then not paying it off is a big red flag.  

I’ve seen the same pattern that @Frank Wong is referring to....a long run-up, then a modest 2-year drop, then a 2-year return to the previous high, then another long run-up.

Find a pattern for what works and copy them.

If you continue to buy at retail pricing you will eventually run out of money and be stuck in a holding pattern as there is no way to get your down payment funds back out of a property with little or no equity.

Applicant’s background must exhibit a pattern of responsibility.Applicant must be a non-smokerIs this being unreasonable?

That's a year long pattern.

Then you have Pattern Recognition which is where the bulk of everything today takes place.

So use their expertise and the more you do this, the more you will start to learn the techniques and patterns yourself.

So, figure out ahead of time how they can pay their rent, as you don't want them to give you a lot of cash, as that could be dangerous to you, if some bad people detect a pattern of you carrying a lot of cash.