Testing for exploits usually requires you to actually try an exploit.

Edit: just to be clear, this is for black box testing.

Upvoted because that's a valid point, but I did consider it before just doing that.

I knew the developers of the site were looking here. I knew there was nothing critical running on this site. They were asking for feedback. Given that, it is much easier to demonstrate the places where it should be fixed than to give instructions on how to recreate each attack.