1. At least one computer-readable storage medium having instructions stored thereon that, when executed by a computing device, cause the computing device to perform acts, the acts comprising: obtaining a set of middlebox error reports relating to a set of middlebox devices having multiple different middlebox device types; separating spurious and duplicate middlebox error reports from a filtered sub-set of the middlebox error reports; correlating the filtered sub-set of the middlebox error reports with other middlebox-related data to produce correlated data; and, performing inference analysis on the correlated data to estimate middlebox reliability for multiple middlebox models within an individual middlebox device type or to evaluate effectiveness of middlebox redundancy.