not a big kid now!

So honestly a little bit of yes, a little bit of no. I actually try hard to make my stuff look more realistic, but sometimes I fail with lighting and rendering, or sometimes the background makes it seem more saturated than what it is. Usually, when someone does wet or mess their diaper, it's not always super obvious, at least not immediately. When wetting, you notice a discoloration. Usually just from the material inside the diaper absorbing the liquid being pressed against the backing of the diaper (the plastic/cloth outer part). It would do the same if you filled it with water. But after a while, depending how yellow your waste is (and depending on how hydrated you are, what your body is filtering out, etc.), it will turn yellowish yes. I mean, not cartoony levels like some artists choose to depict, but yes it's obvious.

More or less that applies to messing. Immediately there's no signs but after, if one goes unchanged, it does show coloration.