It seems to be put together by one guy (instead of user submissions like similar sites) and not quite design savvy at that.
Case in point:
1) http://sloppyui.tumblr.com/image/61441688489 (this is supposed to show "poor alignment")
2) http://sloppyui.tumblr.com/image/61439801745 (this is supposed to show "stray dropshadows" -- didn't they guy get the memo that the iOS 7 UI uses them to show a 3D layer hierarchy?)
3) http://sloppyui.tumblr.com/image/61439835569 (this is supposed to show "poor contrast". Isn't it obvious that the top bar should not be visually striking and distracting?)
4) http://sloppyui.tumblr.com/image/61440586435 (... this is considered "sloppy").
5) http://sloppyui.tumblr.com/image/61440527405 (flat information hierarchy -- one of the few genuine sloppy UI examples).