Combat Gas Mask does not seem to show the "degree of destruction". I found a pristine mask and I was able to put the mask on.

I decided to damage the mask on the purpose. I put the mask in the backpack and shot it with FNX. Backpack got ruined but mask still had an pristine appearance and pristine status.

The only difference was that I wasn't able to wear the mask.

I tried to log out / in, but nothing change.

TLDR: Mask probably can be ruined, but indicators and appearance are not showing it.