Why so much inventory for Rent in South Florida. is it bad to invest???

[Leonard Rybak]

Hi all,   I am interesting in purchasing a property for rent in south east Florida, mainly Hallandale, Hollywood and South Beach.  I have notice quite a tremendous amount of properties listed for rent on zillow and they have been sitting nearly a year .   What is the cause of this?  I am afraid to invest there for Long term rentals as a fear I will be vacant for quite a while.   Is it mainly the location is a poor rental area?  Maybe it more for retirees?  Any input would be appreciated.