Methods of detecting scan avoidance events are disclosed herein. An example method includes measuring, by a weighing scale associated with a barcode reader, an unstable weight over a timeframe having a duration that is greater than a threshold duration. The method further includes monitoring for (i) the barcode reader's failure, during the first timeframe, to transition from a first state in which an imager of the barcode reader does not transmit images for decoding to a second state in which the imager captures images over an FOV including a product scanning region and transmits the captured images for decoding; or (ii) the barcode reader's failure to decode a barcode from images captured over the FOV including the product scanning region during the first timeframe; and generating an alert indicating a potential scan avoidance event responsive to both the measured unstable weight over the timeframe and one of (i) or (ii).