AESTHETIC OR COMMERCIAL APPEAL OF IMAGE While similar images accepted

Rejections for "commercial appeal" are highly subjective on the part of the Moderators and what appeals to one might not appeal to another. Unfortunately, there is no way to dispute their findings, so you'll just have to move on and accept it...

Rejection for Commercial/Aesthetic reasons = it's not what Stock customers are buying.

Accept it and move on...

Try submitting it to another service.

Well, I guess the moderator doesn't think it will sell. Different moderators may have seen your other images and had a different opinion. I personally don't think it has a lot of potential. Another point is that if you have a lot of similar images, it can also be rejected as being similar to other images.

The moderator might have had a choice between the rejection reason you mentioned and that of Quality Issues and decided to flipp a coin. There are issues with the eye and what appears to be a scar of some sort on the ear. And the blue and red splotches between the ears, which I personally would have removed.