Whenever you have a property where the amount of rent it makes takes covers the cost of the mortgage, insurance, property managers, utilities (if owner pays), and taxes it is considered to be cash flowing. These properties could be counted as an asset because they are making you money above and beyond paying for the property.

The amount of cash flow will vary and depend on each individual property. Location is huge, and the rate of cash flow can be tied to the amount of risk you are taking on. Personally we won't consider buying a property as an investment unless we're able to bank an extra mortgage payment every 3-4 months at the very least.

Some people are just happy if the mortgage and taxes are covered, but it really only lasts so long... until there is damage or something like a roof or furnace needs to be replaced. When people owe too much to sell a home they might be forced into a situation like this. Even though it's not necessarily ideal it's a short term solution to the problem they are faced with (for instance they had a job relocation).

Let us know if you are interested in learning about these properties, they aren't for everyone but people that have them often have more than one.