If your unsure of an image you should do a google search for it, to compare it to others and never compare an image with another image from the same person. Unless you're spotting a hair or a scratch that appears on more than one of their image. Then you can tell them to clean their scanner and why.
Unfortunately, this happens on a lot of websites when you outsource people to do the art when they do not have an artist's eye. I do work at fanart.tv and they have a system where two people have to approve an image and if you let too many bad images in, you are kicked off the approval board.
They have a simple way of looking at it. Just because you have an imaging system does not make you an artist. After all, you would not go to a butcher's to have a kidney transplant.
It takes a lot of time & practice to be good at something and a good decade to be great at it. If you're not willing to put the time in to be good at something, you should be doing something else.
Two people to approve an image will bring up the qualty and having a way for the two to communicate will also improve their ability. This is where a chat room for the website comes in handy. Even if people in the chat room are not doing images. you can post a link and ask what do you think about this image if you are unsure. You will get quick feedback and production & quality will go up.
Most sports are a team effort and it takes communication in the team to be great.
What is that behind you!?! Oh, It's me! Looking at the cards you have, That I want. :)