It's an interesting subject, though I'm probably looking at it from a different angle than you guys... ie more psychological than philosophical. Specifically, I'm thinking about idealisation and devaluation; those processes don't (imo) create good or bad out of something that was neither before, but rather focus your attention on essentially objective properties of the object... so object O with properties a, b, c, x, y, z... could in one circumstance be idealised, bringing properties a, b, and c positively to mind while ignoring or minimising x, y, and z, but in another circumstance, could idealise x, y, and z, ignoring or minimising a, b, and c... or vice versa with devaluation (ie focusing on negative properties and ignoring or minimising the positives). And in this, the 'circumstances' that change are different needs and conditions at different times and it could be said then that at any given time, you only have a partial representation of an object accessible in your mind (to feel anything about... like/dislike, desire/aversion)... ie the properties you have idealised or devaluated based on your current needs. But the properties themselves are (or seem) objective; water is wet but it generally requires feeling hot and/or thirsty to idealise water bringing that wetness to the forefront of your mind as a positive feature... remove or satiate that need and that property is no longer idealised... and perhaps even devalued... and in my case, the 'bland' negative property of water usually resurfaces and I look for a more tasty drink 
