True, but (a) they were typically experienced investors, and (b) today's market includes record prices and high mortgage rates, which is a double whammy. 

Buying a second home to rent out is a solid strategy, but be sure you understand the cash flow, including mortgage, taxes, and potential vacancies.

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

We typically pay somewhere in the range of $3500 for a new, basic furnance, including install, if there are no other modifications to the system required.  

There is roughly $20,000 left in rehab including windows, floors, a new kitchen and bathroom. 

Many of our clients, including myself, have done that.

My target market is South Florida, including Miami-Dade County, Broward County, Palm Beach County, and possibly Collier and Lee Counties.

If you are looking to just calculate profitability, set how much profit you want to make then:ARV - Purchase Costs - Holding Costs - Selling Costs - Desired Profit - Rehab Budget (including contingency) = Maximum Allowable OfferIF you cannot calculate those numbers, a spreadsheet isn't going to help you. 

I've included an example below to help illustrate this.So different lenders have different rates (which do vary even for DSCR loans) but these are factors they all consider.See example below:DSCR < 1Principal + Interest = $1,700Taxes = $350, Insurance = $100, Association Dues = $50Total PITIA = $2200Rent = $2000DSCR = Rent/PITIA = 2000/2200 = 0.91Since the DSCR is 0.91, we know the expenses are greater than the income of the property.DSCR >1Principal + Interest = $1,500Taxes = $250, Insurance = $100, Association Dues = $25Total PITIA = $1875 Rent = $2300DSCR = Rent/PITIA = 2300/1875 = 1.23If a purchase, you also generally need reserves / savings to show you have 3-6 month payments of PITIA (principal / interest (mortgage payment), property taxes and insurance and HOA (if applicable).

Through my journey I have gathered priceless information about the markets and maintained countless of connections including contractors, investors, agents and brokers.