Similar happenings reported here: http://www.reddit.com/r/dayz/comments/1xwegm/possible_bugs_pants_ruined_for_no_reason/

I had yesterday the same problem.
I was in the jail, no opponent, i saw gray like a hit, my pants was runied but not the the items inside.
I was in the corner out of the range of a window, so unable to get shot.
I was already healthy and nothink else happens. Only my pants was runied without a reason.
My girlfriend was at the stairs and also saw nothink and no reason. There was also no bug-user in the walls.
We have no idea why this happens

How do you know that those gunshots were not directed at you? Something like that already happened to a friend, he thought he heared gunshots, his pants were ruined. I told him it was probably a sniper, a few minutes after that he got abducted by rapist poles.
Pristine stuff actually protects you from gunshots, I think that if the guy opens fire from a very long distance, the pants might have taken all the damages from the shot. Also it could be an invisible zombie under the floor. I know that if you go on the third floor of office buildings, and that they remain on the first floor, they can still hurt you brom beneath.
Yet this ruined pants problem also happened to me in a isolated place with no one around, and no zombies in this location.

Short falls, not enough to break legs, but to cause minor health loss may cause damage to pants. I try to not carry anything important in my pants with the current builds.

when I heard the gunshots they were off in the distance, and I didnt hear any bullets hit near me, also later I ran into a guy that had a gun and told me he was shooting at zombies. Also after this event, I went out and found another set of pristine autumn hunter pants and I noticed an immediate difference in color and on the ruined pair the knees looked worn and faded, I remember first seeing this after crawling around, I was in first person and I looked down and saw the faded knees. Can crawling around affect the state of clothes? They probably got ruined when walking down a set of stairs but I really dont know what truly happened.

I experienced this in the Municipal office in Novodmitrovsk. I was looting on one of the platforms between two stairs. So I didnt move when i got damaged and nothing happened on the way up that could have caused it. The only way i could get shot was if someone stood in the stairs cause i were covered by walls all around and noone was in the building. Pants and content in pants got ruined and my backpack went from prestine to damaged but nothing inside took any damage.
I have had the same happen two times in the firestation tower and a few times in residentialbuildings

I think it's the same issue that causes people to break their legs. Sometimes you just don't get enough damage to break them and only your pants end up ruined. Sometimes you end up taking enough damage to die.

I've had this too, but also generally clothes I'm wearing going down a tier-level when I re-join after reset for example.
Did you have to rejoin or did you join another server, too before they got ruined?

it happened also to me, I think it must be the crawling that damages the pants, which in a way it's also logical, maybe not so fast, ant the interior should not also be ruined, but that pants take damage from crawling seems correct after all

this has happened to me twice. Not all items ruined. I am checking everytime I walk down steps now, because that is the only activity i have been doing that may cause it.
ruined pants, ruined boots. 0.49

Hi survivors,
thank you for your feedback.
This is something we are continuously investigating but identifying the exact cause might take some time - please be patient and feel free to provide any possibly relevant information.
Regards,
Andy

I've had this happen twice as well, both times going into the bunk room of a jail building and both times shoes and pants that were pristine were destroyed along with all contents.
The second time my legs broke as well.