Fair enough. That said, I wouldn't jump to conclusions on how things like saturation or desaturation play into ratings, a lot of instagram filters for example

Fair enough. That said, I wouldn't jump to conclusions on how things like saturation or desaturation play into ratings, a lot of instagram filters for example have an a desaturation effect which makes me wonder if folks like that as a look. I don't personally. Very well could be a bad model, but sometimes there are underlying factors that result in these bad models from the training set. And no, it's no ML 101 to randomize elements of your input in the training set, though if you want a broadly applicable model you'd look to have inputs that include a variety of hue and saturation (perhaps that's what you meant - I have seen folks though manually start doing things like randomize hue in the set, where the ratings were on the original image).