Most people say they care about buying ethically. In fact, 55% of the world’s online shoppers say they would be willing to spend more for ethically and sustainably produced goods and services, according to a 2014 Nielsen survey. But do they make that choice in real life?

That survey, which polled 30,000 consumers across 60 countries, found these principles do translate into sales, but only slightly: Products with sustainability claims on the packaging saw sales increase 2% in March 2014 compared to the year before, while products without such claims saw a rise of only 1%. If a product had a marketing campaign focused on sustainability, it got a boost of 5%.

These results are encouraging, but limited: They focus on what consumers say, and not necessarily what they do. The survey also focused on how shoppers respond to marketing and packaging ploys, which can be misleading. What would shoppers really choose, especially if they had to figure out whether a product was ethical or not on their own?