I’ve noticed that when I knit round objects such as an amigurumi doll head or just a simple ball, I can see the stuffing through the stitches. I’m wondering if I’m decreasing too loosely or maybe it’s because I’m not using k2tog and SSK together? I’ve just been using K2tog and there’s a gap between the stockinette stitches. 
Decreasing too loosely in the round?
Since it seems like a ladder of loose sts, I think it’s more than the decreases. It may be the joins between your double pointed needles? You can try tightening up just a little on the first st of the needle or try knitting a st from the next needle as you go around. That way the ‘join’ travels and doesn’t stay in one place. All k2tog won’t cause a ladder.
It looks like you need a smaller needle though; things like this should be knit more densely so the stuffing doesn’t show through. As well as ladders from knitting in the round.
Well, I’m using a long circular needle and it’s a size 7. Hmm, I’ll try joining more tightly to see if that helps. Thanks!!