There's strong reason to believe sweatshop labor is a positive thing, actually- both conditions and pay tend to be superior to other options available in that location, and sweatshop owners expand the middle class. Similarly, the push to exclude child labor in sweatshops hurts children (and their families) in developing countries, because the choice is rarely "work or go to school" but instead "work at a good job vs. work at a bad job."
Which is one of the reasons why something like this would very quickly devolve into a political battleground: there are legitimate differences in opinion (even if there aren't illegitimate ones will get presented) and who comes out on top has real-world implications.
Lately I've been thinking about all of the various services and products I consume and how pretty much all of them are bad for the world in one way or another, large or small. Some of the problems associated with them I am less concerned about. Some of them could be construed as good things (i.e. sweat shop labor DOES provide jobs, whatever impact it might or might not have on the overall quality of life).
In general I'd like to live my life having as minimal a negative impact on the world as possible. But "negative impact" is a hugely broad topic and there are a million variables to consider and I just don't have time.
The best solution, I think, would be to have a wikipedia-like website where individual people with knowledge of specific problems can start tagging specific products with the types of negative consequences associated with them, and (somehow) sort those consequences into categories that individuals can decide how much to worry about. Over time it could eventually become a fairly efficient way to track the utility value of things.
I'm sort of hoping something like this already exists, even if in an infant form, and that someone here knows about it. But I doubt it, so the I guess this falls mostly under the post category of "hey someone other than me should devote a bunch of time and energy to this project that I myself am not qualified to do." But maybe a few people here at least have a better idea than I do of the scope of the requirements for it, so the idea can be refined a bit.