At what point will the banks cut you off?

[Greg White]

I know one of the strategies I hear frequently on the BP podcasts is to purchase a single family home investment property, fix it up to increase the value and then refinance - taking profits to use as a down payment to purchase another property, presumably right away. The question I have is, "How many times can an average Joe do this until the bank lenders consider them over extended?" After all, every time you accumulate a new rental property, you in turn increase your debt on paper substantially and you also presumably affect your credit score in a negative way.  So in-general, could one "really" expect to acquire an unlimited number of conventional mortgage loans for single family home investment properties - as long as you can produce a 20% down payment??