Addressing inarticulate needs in addition to basic needs satisfies better the customer. Therefore, in assessing the quality of a service, we propose a blending between the background knowledge of the client, his current expectations, concrete observations on its interaction with the service, and interpretations of these observations. The pair description-situation from foundational ontology Dolce + DnS supports an homogeneous and integrated representation of both direct observations from SOAP messages and also interpretations of these observations according to the current context and knowledge. Expectations are the instrument for monitoring the client's interaction with the service, and for assessing its perceived quality of the service.