You can see that, for example, from the dark color of the sheet after the wash (see picture above). I've personally tried some of these products (see my reviews below, along with other people's) and I have seen that they do collect dye. Here's the video from Consumer Reports showing their tests of two of the most popular brands of this product, Shout Color Catcher and Carbona Color & Dirt Grabber, and how they worked in comparison to just washing the clothes without the product included. While some people swear by these cloths (see some of the reviews below, for example) other authorities (namely Consumer Reports) say that these products just don't work as promised, and you should just save your money and sort your laundry like we've always been told to do before. The short answer to this is that people disagree. The million dollar question, however, is do they really work as promised? These color catchers promise a lot, like being able to wash all your clothes together, including a bright red garment with your whites. The cloths don't do that, but instead are just supposed to grab dye from the wash water.

Please note that these catchers are not the same as dye or color remover products, which grab dye from fabric itself.

Therefore, a special type of laundry product has been created to try to fix this problem - little pieces of cloth specially formulated to grab bleeding dyes in the wash water and keep them from redepositing on other clothes.

Color grabber laundry