What Can You Say About This Scaup?

I'm confused by the plumage of a Greater Scaup I observed and photographed earlier this week on the Jordan River in Sandy, Utah. My first impression was that I was observing a female Greater Scaup when I saw the brown head with a contrasting white patch at the base of the bill and forehead. We don't often see Greaters in my part of Utah so I often try to sift through the Lessers to find the Greaters--I'm not referring to the people of Utah :)   It's much like sorting through hoards of Canada Geese hoping to find a Cackling or Greater White-fronted Goose.

I'd love to get some feedback (leave a comment below) on the sex of this bird because it exhibits plumage characteristics of both male and female. The head looks very female, but the body is quite different from female yet not really male either. I searched my field guides and checked for images on the web and was left scratching my head. I found one comment on the web about older female's taking on male plumage. Some of my local birding experts suggested older female, brighter female, and juvenile male transitioning to adult breeding plumage. 

I've included male Lesser Scaups in most of the images below for comparison. The last two images include the Greater AND a Lesser Scaup with similarly confusing plumage. That particular Lesser's head is notably darker so I wonder if we have juvenile males transitioning to their first adult breeding plumage. None of my field guides show much about 1st winter/spring males. Did I mention I was confused? The bird on the right in the last image has quite messy plumage in case you want to comment on that one.  I'm not sure if he's trying to change into our out of his breeding outfit.

I look forward to reading your comments below if you have experience with this plumage