I watch the screenshot uploads....and can recognise those who take special pride in their 'creation'....there's a sort of sub-set of people at WC who specifically enjoy creating them.
Others just use them as a tool to show people where their skins are at in terms of creation/development....they're the skinners using the 'tool' of a screenshot.
Those skin users who wish to display their creativity in collecting/setting up their shots.....I personally rate as if they were any other form of submission...though 'personal taste' does not stop me appreciating those 'feminine' styles will be liked by the ladies, etc and are rated accordingly.
Anyway...to answer the question....a '10' [5 star] rating would be for something genuinely original...often with a new, never before seen skin, and or quality existing skins selected to suit properly as an integrated theme.....as the screenshot is supposed to be a 'skinned GUI' therefore the entire GUI should look fresh and entertaining and co-ordinated.
My personal view of screenshots is that they are an essential 'tool' in skinning....and always have been. But...others like to use them as self-expression.
Perhaps what is needed is two screenshot sections....one for function [tool]....one for form [rated appearance].
Or is that going OTT?...
I am a very biased person. However, when I rate things, I don't go by who makes the skin or theme or whatever. I go by what I think of the content. Even my good friends on WC I will give a low rating to while giving a high rating to users who get on my nerves.
'Knowledge' comes through frequency/familiarity....there's two ways of drawing attention to yourself....by consistently 'getting it right' [site/community interaction] or by consistently 'getting it wrong'.
The latter is not a good survival characteristic, however....