In some cases the owners had to move because of a job transfer, etc and realize that they cannot afford to sell the house because they owe more than its current market value. The owners then may decide to rent the house so the monthly rent reflects what they need to make their mortgage payment, taxes, insurance etc.
I believe the decline in market for the past 5 years has made the demand for rental homes much greater. Many people have lost their homes and must rent. Many Coast Guard personnel have decided to rent rather than buy because the real estate market has not bounced back and they may not be able to sell a home when they are transferred. All this has put pressure on the market for rental homes and, therefore, the monthly rental prices have gone up.
I am guessing there is a correlation between amount paid for rent and condition or location or both. Less rent usually equates to less as far as condition or location. It is a fact of supply and demand.