In the last three weeks we have accepted two offers from prospective tenants and both have fallen through at the last minute after they have been referenced checked. The letting agents have said it's because their circumstances have changed (don't know if that means they have found somewhere else or they can't afford it./doesn't suit their requirements anymore because the letting agents won't tell us) and not that they failed the checks. We're new to this landlord thing so is this quite common?