Smear? like at the bottom left? Thats just me pressing and dragging. You can see where the strokes are heavier.
If you mean the purple on the left hand side, that's from stippling on an image on the next page, it just bled through.
same with the blues on the top half of the picture, thats from a picture on the previous page.
But you need to blend quickly while its wet so that the colors can melt together, is the only advice I can think to give. Especially if youre blending more than a few colors