Determining if a house is used for rentals

Hello BP community, I am moving much closer to purchasing my first deal.  Well, actually doing much more targeted research now as opposed to only education.  In any case, my question is, how do I determine if a home is being used as a rental property?

I have looked through my country tax assor to see which homes are being taxed as multi-family (whiche means they must adhere to code in my town, ie kitchen in each unit, bathroom etc).  However, I have not been able to confirm if these homes are in fact being used as rentals.  Any advice would be very helpful please?