Examples described herein relate to selectively forwarding traffic flows based on traffic flow classification. Examples include classifying a traffic flow into a first traffic class by a first machine learning (ML) model based on flow characteristics of the traffic flow. A second traffic class is determined based on a deviation between the flow characteristics of the traffic flow and average flow characteristics of each of the plurality of traffic classes. A quality metric for the first ML model is updated based on whether the first traffic class and the second traffic class match. The traffic flow is selectively forwarded based on the quality metric.