All properties are different, but simply put, you will either show a profit or not.  Traditionally, most businesses must part with an average of 30% of earnings (income) just to pay the bills or COGS (Cost Of Goods Sold). The COGS usually include your utilities, insurance, products that you may buy for resale, janitorial supplies, office supplies, chemicals for pools, and other general maintenance supplies.

The list goes on.  It does not include your mortgage and any personal expenses.  Keep this in mind when looking at the bottom line figure called net sales.  Net sales are what is truly your profit after all expenses have been paid.  Most P&L structures will show a mortgage in it if they have one.   Keep in mind that that amount shown is usually only interest.  You cannot write off the entire payment as the principle amount becomes an asset, which is transferred over to your balance sheet.

The quickest way to determine if you can afford and live on what they are showing is to be certain there is a NET profit (not in the red).  Then circle any expenses that you may not acquire after ownership such as interest on loans, depreciation (since this is commonly joined in the family of cash flow), medical insurance payments, auto loans and/or leases.  Add these expenses to the net profit and then subtract any additional expenses you may incur.  Don't forget to also add in your mortgage payment in full to justify a true profit. If you feel this is feasible at this point and you want to proceed, then it is definitely time to speak to a CPA and verify all information and numbers.