One of her boobs is missing...

That's because her ponytail's covering it

gabriellapuratekuta said:
That's because her ponytail's covering it

My instinctive revulsion tells me that more of the boob's presence ought to be visible and that the artist screwed up.

The artist did screw up. By making the right breast so distinguished - she's flat.

BerZerKer said:
The artist did screw up. By making the right breast so distinguished - she's flat.

If you're talking about the left then I'd understand what you're saying. But artists make the mistake of not shading breasts correctly. Even semi-flat boobs have shading under them. :3