In one embodiment, a device receives optical time domain reflectometer (OTDR) trace samples, each sample labeled with an associated fiber optic cable condition. The device alters the received OTDR trace samples to generate a set of synthetic OTDR trace samples. Each synthetic sample is labeled with the label of the received sample that was altered to generate the synthetic sample. The device trains a machine learning-based classifier using a training dataset that comprises the synthetic OTDR trace samples. The device uses the trained classifier to identify a condition along a particular fiber optic cable based on OTDR trace data obtained from that cable.