There's Something Wrong With This Map
And I'm pretty sure I don't have to tell you guys what it is.
(No, its not the pink fullbright or whatever, too lazy to close/open Portal 2 to fix that)
Everywhere.
If you ever want to move a large part of your chamber, make sure to put texture lock on.
What exactly was this thread about? was it that kind of game based in "find the 7 differences"? "find the 7 mistakes"?
useful tools and stuff here on TWP 
[spoiler]
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If you think that's bad, don't play the first map I made.
My Work
[spoiler]Maps:
Revenge of the Angry Turrets
Capture the Cube [Co-op]
Capture the Cube 2 [Co-op]
TPWEGTH Sample Map
Aperture Aquatic Testing Center
Aperture Aquatic Testing Center 2
Aperture Time Testing Center
ML's Halloween Trick - 1000 downloads!
ML's Halloween Treat
ML's Combination - 1000 downloads!
ML's Jailbreak Labyrinth
ML's Tricky Teamwork [Co-op]
WIP:
"Capture the Cube 3"
Workshop Maps Link: http://steamcommunity.com/profiles/76561198008890579/myworkshopfiles/[/spoiler]
I think you're supposed to talk about your own bad maps here. I'll start.
My first map had a big box around it. It was all one room, a really bad a4 looking map. I didn't use 128, 256, 64, ect. All the textures were dissaligned, all the white was a separate brush 1 unit thick. No nodraw in the map. And. The worst part. No cake. And portal 1 lighting/ random lights in the air. The link to the PeTI version is in my signature, because I don't feel like remaking it. It has a good puzzle though. And I released a map called emancipated polarity a while ago. Someone put screenshots of that up.
GIVE MORE BAD MAP STORIES AND PICTURES!
About the first picture: That target panel looks too thin, and what's holding it at that angle? 
At the moment I'm making a map which requires a big skybox-textured cube around everything, which feels frustrating, but I can't find a way around it. I need a sort of Bastion-like platform in the air, which the player can fall off of. 