@Shayan Sameerif you borrow 100% of the purchase price, then you will likely lose money no matter which market you buy in. 

The Chicago Association of Realtors'® specifically state "When you become a Dual Agent, you owe equal fiduciary duties at that point to both parties in the transaction, and you lose the ability to negotiate for, strategize and advise either one."

Overpricing will likely lead to longer vacancies and lost income.Respond QuicklyTenants have more choices than ever, and properties that don’t respond to inquiries promptly may lose out.

People like to use HELOCS especially now, if they have a very low interest rate first position mortgage, in order to tap into that equity without losing the low interest.

However, I’ve witnessed cases where the investor went “all in”, spending and losing many millions.  

@Rafael Ramos All your goals contradict each other:(1) Cashflow: buy Class C & D properties2) Appreciation: buy Class A & B properties3) Low Crime: buy Class A & B properties4) Why would you want your investments to lose money to lower your taxes?

So, I've closed hundreds of loans for people. 

When that happens you will only lose part of your cash flow rather than all of it if you have multiple DSTS vs one larger one.

You are LOSING money because you didn't even raise rents to cover those increases!

That’s assuming you don’t lose money to vacancy, capex, etc etc.