It is something that can happen, but probably isn't the most common thing people see with IBS. However, every weird stool that can happen to people usually eventually does if you have IBS long enough. It seems logical that this stool variation should tell you something about what is going on in there, but it just reinforces you have IBS, and every weird stool can sometimes happen to healthy normal people.I will say sometimes you have to be careful with the "I didn't eat that color" as some colors are secondary (like there can be a lot of orange in dark green foods that you just can't see) and other colors will change when they go through the high acid and then being adjusted back to a neutral pH. Those color changes with pH are sometimes used to measure pH and it is a fairly common thing so sometimes food dyes do some pretty interesting things in there that you wouldn't expect.