If they were scraped from Discord where others posted them, then they are scraped from a filtered source which contains only cherrypicked pictures that people chose to post, the ones they found interesting and good - it would be representative if and only if it had sampled also the pictures they generated but did not post.

"representative" is not the same concept as "unusable", so you should not put quotes around that text.

It's like going to the grocery, seeing a bin of beautiful apples and saying "every apple on the tree is beautiful". You can't draw that conclusion because those apples aren't representative of all apples because they went through a filtering process. In this case some one choosing to sell them. Upthread, some one choosing to share them.