You cannot analyze oil by looking at its color. Oil chemistry is complex and unique based on manufacturer and application. Some oils maintain their color throughout their "life" while others change color immediately in the presence of heat or byproducts of combustion.
Certainly if you know that you have problems, like it running rich and smell the presence of fuel during an oil change, then yes, you have a number of indicators of a problem and likely, oil color will support that.
Engine internals, such as your valve train or valve covers, can give an indication of a problem.
I use Mobil 1 and find that it is generally dark in nature as is Castrol Syntec.
Personally, I would stay away from flushes or whatever and just continue with your oil change routine with quality oil. Manufacturers of oil and engine builders also recommend that you do not switch oil manufacturers; if you are on Mobil 1, you stay with it. Again, oil chemistry is complex and incompatibility between oil chemistry can be harmful.