Invisible small mess in Waste Disposal

[-silver-]

Hello, I recently started noting that the Sniffer detects a small mess in the big pipe corridor on the right (I don't know if it's junk, a decal or a bullet hole) even after I completely cleaned the entire map or just that area.

This is the place: http://i.imgur.com/wgm8UDy.png

It's the second time that this happens to me, the first time I thought it would be some random little glitch that would go away with a game restart but it persisted.
I even tried to verify the game's cache files and it didn't work.

I have tried to spot it with patience and effort: I have checked the area meticulously with the lanterns, I have used the mop in every single small spot, I have used the "ghost" cheat to see if something fell through the floor and I have even changed viewmode to search better for any decals or bulletholes but the sniffer continued to detect something while I couldn't find anything.

Despite this all, the cheat "killnearestmess" did work, but that just still leaves me dissatisfied because I still don't know where and what was that mess.

Here are some screenshots:
http://i.imgur.com/p7xEirc.jpg
http://i.imgur.com/zmPY6N6.jpg
http://i.imgur.com/oM5tDq5.jpg
http://i.imgur.com/KlfkyNK.jpg
as you can see I kept the sniffer in junk mode because this is how it detects that

However in this viewmode (which I don't know how it's called) I can still see other messes:
http://i.imgur.com/01dquk9.jpg
http://i.imgur.com/njigNF6.jpg

I know it's not a big deal but these little things annoy me a bit.
I do not require this to be fixed immediately but I'd appreciate if you are willing to help me. ^^

[BlackEagle]

I'll investigate the area and see what's causing it.

*EDIT: Couldn't find anything immediately apparent in the editor. Will do a cleaning test to see what happens.

*EDIT#2: Yep, couldn't find anything invisible, although the messes can be very hard to see normally. It's possibly the "Sniffer" was detecting an object not in that pipe, but rather on the other side of the pipe wall, in that passageway in the other part of the level where the Big Banger is. There were some hard to see bullet holes there that set it off through the pipe wall.