Reduce Asking Price for House

[Andrew Merritt]

I'm trying to rent out a house and I'm afraid I may have put the rental price too high initially (I was a bit too optimistic).  I have one couple who have applied, but their credit score is below 500 and I'm not confident in their ability to pay so I'm very hesitant to rent to them.  

Anything I should be aware of before dropping the rent down?  I'm probably going to drop it down from 1800/month to 1700/month or less.  Also, I'm in Summerville, SC if that makes a difference.