So I got a Gas Mask (Damaged), I was eqquiping it didn't fit quite well. You have to see the screenshot to understand since I can't explain it.

It wasn't like that all the time, but when I looked with the mouse to certain areas it appeared like that. I can say it was like that 80% of the time.

After that I traded it with my friend to try to reproduce the effect and he said it was ok for him.

He didn't see as I did, but looking at him wearing the mask and running around, sometimes the mask was showing floating just behind where he just walked, just for a moment.