We argue that the incorporation of cloud service brokerage (CSB) mechanisms will strengthen the resilience of services in cloud-based VEs. In this respect, we present the Service Completeness-Compliance Checker (SC3), a mechanism which offers capabilities with respect to the Quality Assurance dimension of CSB. More specifically, SC3 strengthens the resilience of cloud services by evaluating their compliance with pre-specified policies concerning the business aspects of their delivery. By relying on an ontology-based representation of policies and services, SC3 achieves a proper separation of concerns between policy definition and policy enforcement. This effectively enables SC3 to perform policy evaluation in a manner generic and agnostic to the underlying cloud delivery platform utilised by a cloud-based VE.