I've spent close to 50 years using dip cleaners on carburetors, and dark color usually indicates lots of suspended dirt. Try pouring the cleaner from one container into another and strain it through an old t-shirt or something similar. If you get a bunch of sediment, that's not a good sign! The commercial-type cleaner in the 5-gallon bucket usually has a layer of water a couple of inches deep on top, to keep the cleaner from evaporating. The difference in specific gravity and chemical content keeps the water and the cleaner from mixing.
One precaution- - - -carb cleaner is highly toxic, and it will dehydrate flesh alomst instantly. Do not get it on your hands! One of my students got carb cleaner on his hands, and went to the restroom to wash it off, but he decided to take care of some personal business first. Bad idea! Carb cleaner on "sensitive" skin gets painful, instantly! He had to go home and shower, RIGHT NOW!
Jerry
