A system persistently presents consistent properties of devices on a local network based on observed values for the network devices, and values derived from the observed values. The observed values may be received from an agent based on scans of the local network. Even though some scans may be faulty resulting in missing or incorrect data, a user can be consistently presented with properties of the device, even when the missing or incorrect data would otherwise cause a change to the property. For instance, the system may replace a data value that is either missing or determined to be incorrect with a value that is determined, based on historical or lab observations, to be the likely correct value based on the assumed state or likely state of the observed device.