One variation of a method for tracking promotional states of slots in inventory structures within a store includes: accessing an image of an inventory structure within a store; detecting a shelf tag on the inventory structure in the image; extracting a set of features from the shelf tag detected in the image; detecting a promotional tag on the inventory structure in the image; extracting a set of features from the promotional tag detected in the image; detecting a deviation between the shelf tag and the promotional tag based on a difference between the sets of features; and, in response to detecting the deviation between the shelf tag and the promotional tag, identifying the first promotional tag as erroneous, and notifying a store associate to replace the first promotional tag with a second promotional tag at the first slot, the second promotional tag correcting the difference.