Mortgage qualification, new investor

[Chad Longley]

I am wondering about mortgage qualification parameters on investment properties. Do banks assess the rental income potential on a property when they qualify you?  In other words, I hear all these stories about people buying multiple properties in one year (not that this is my goal), and getting multiple mortgages over that one year span of time. 

I am only familiar with owner-occupied real estate, where the bank qualifies you based on your gross income against all debt payments (i.e., front and back end ratios).  I've only ever owned one home at a time.  

For investment properties, do banks actually consider potential rent as income?  I am just trying to figure out how a people with limited means initially get multiple mortgage approvals--my only thought is that the banks must consider the potential cash flow on each given property.

Any advice on how the mortgage approval process works would be much appreciated.  Thanks all!