1. A method of operating a workstation having an imaging sensor located within a housing that has a first window in an upright plane and a second window in a generally horizontal plane that intersects the upright plane, the workstation having two modes of operation including a barcode-scanning mode of operation and a monitoring mode of operation, the method comprising: projecting illumination light through one of the windows by energizing a illumination light source within the housing, intended for capturing at least one image with the imaging sensor; capturing multiple monitoring images each being captured with the imaging sensor while the illumination light source is energized during one of multiple monitoring exposure-time-periods associated with the monitoring mode of operation, wherein each of the multiple monitoring exposure-time-periods is below the threshold exposure-time-period, wherein the threshold exposure-time-period is an exposure-time-period that allows the imaging sensor to capture first patterns of a barcode with said first patterns being decodable when said barcode is in direct contact with said one of the windows while the illumination light source is energized, and wherein the threshold exposure-time-period is 110% of a sub-threshold exposure-time-period that allows the imaging sensor to capture second patterns of the barcode with said second patterns being undecodable when said barcode is in direct contact with said one of the windows while the illumination light source is energized; and detecting a checkup-condition including analyzing the multiple monitoring images to determine the presence of at least one image of an adverse feature that includes a piece of dirt, a scratch mark, and a spill mark on said one of the windows.