there's never anything of stupid high quality so it's a very easy scale for what's grown around here.
price, irrelevant, you get what you ask for
smell, irrelevant, it's not cured and whatnot propperly so they all smell the same on the whole
colour, irrelevant, colours can mean pretty much anything from my experience
the only thing that is a determining factor for the stuff is it's consistency. you squeeze and it's solid, you know it's generally gonna be a good smoke. if it's airy, it's generally a bit of a let down and a bit of a crap deal (a lot of dealers like the idea of physical size rather than weights which sucks as half of them buy cheapass airy weed)
i guess in the UK there isn't really such a thing as bag appeal though. 95% of times there's the 1 bag that you can't choose from, so you get whatever your bloke has, wheras in the US you might be talking a dispensary where you're spoilt for choice.