Service level agreements (SLA) are contracts defining the obligations and rights between the provider of a web service and a client with respect to the service’s quality. An essential component of SLA management is the run-time checking of relevant quality parameters. SLA checking must be precise and continuous to timely detect any possible SLA violations. Available techniques and mechanisms to check SLAs, however, are unlikely to scale to more complex families of SLAs tailored to fit diverse and very large groups of clients whose devices have limited storage and bandwidth capabilities. This challenge results not only in the commitment of valuable resources to SLA checking (reducing the service provider capacity), but it can also trigger additional violations and cause disagreements between client and server due to perceived violations. In this paper we focus on the elaboration of this challenge and on identifying opportunities that arise from the inherent diversity present in scenarios rendering web services in pervasive environments.