Why so many headphones for sale with less than 10 hours of listening time?

I've been in the market for a new pair of headphones recently, but have noticed that an unusually high percentage for sale are classified as "mint with less than 10 hours of listening time".  What gives?  How could anyone possibly make an accurate assessment on something with less than 10 hours involved?  Audeze is one of the brands I'm considering, but it seems like this is the one that has the most for sale with little time involved.  Could it be a comfort thing?  Any insight would be appreciated.
it could be disappointment ,not all peopleknow abaut burn in time.People expected wow sound,did not like how favorite tracks sound
A lot of people just aren't headphone people, they jump into the game and still listen to there main rigs as their source of music and the headphones just sit,then they need something for the main system and sell off unused gear to make the purchase. You mentioned Audeze as one that gets moved with low hours and I noted that as well when I purchased a pair of the 2s from a guy that was moving up to the 3s. Toyota has sold a shitload of Cambrys so it would make sense that there would be a lot of them in the used market.

All good points tooblue.  I get that people purchase them and still listen to their main rig 99% of the time, but I've also read that the Audeze phones are heavy and bulky.  I'm not picking on Audeze, but until I can get to try a pair personally, I'm trying to figure out if it's something more than that.
Headphones actually take a long time to break in.  People don't realize it so they sell them because they sound thin.   My Sennheisers (HD650) took 500 hours to sound decent, and another 500 to blow my mind.  I can see someone selling them after 100 hours and buying Beats (and my laughing until my side splits).  
Sense62, to address the issue of comfort on the Audeze, I have really enjoyed mine quite a bit over the few months that I have owned them and have used them hours on end with no issues with comfort, I use them with a Yamamoto H-2 tubed headphone amp that is very impressive in it's own right. Let me also say that I do not consider myself a headphone guy but did want a really good set in my retirement system for future reference and listening. I used the forums and reviews to choose the Audeze but I am sure there are a lot of other flavours in and around their price. 
In my case I read about headphones and heard raves from some people, so I thought I would try them out. Bought a nice pair and a headphone amp to run them. After listening for a while, and trying some very expensive headphones, I decided that I like listening to my speakers much more than any headphone I have heard. I would use them if I had to, but other than that I would pass.
First, I would be highly skeptical of any number of hour claims. Frankly, take them with a grain of salt. Next, there are quite a few headphones that initially sound impressive but with headphones, much more so than most other gear, listening fatigue sets in fast. For instance, those crystal highs turn out to be a nasty rising high end that makes the cans unlistenable over the long run. And that impressive bass, drones and drones. I also think that few people have adequate amplification for their headphones which quickly leads to disappointment. Finally, I would guess that many people buy headphones on line, based on reviews, and without any audition. By the time the return period is over, the honeymoon is also over. 
I could easily avoid this topic but I do have a comment. If someone wants to purchase any piece of high-end audio equipment (at full price), then sell it after only 10 hours use, I'm happy to buy it from them at 50% (or less) of their original purchase price. That's the basis of this website. People are impulsive, and (sorry for the cliche) their loss is my gain. No one forces them to do it. Speaking of headphones, I purchased a pair of Stax 009's on this site for about half of retail. They were practically new and came with the wooden box, extension cord and cover. No complaints here! 
Personally, it gives me no pleasure of taking advantage of imbeciles, either impulsive or not. Those people need help not being ripped off.
I have asked myself the same question!  I recently purchased a LCD3 w/ "less then 10 hours" on them.  And I am absolutely loving them!  While I can't confirm the validity of the usage, I assume now that issuing that statement "less then 10 hours" also means "these are in great condition...I may have used them for 500 hours...but you would not be able to tell."

Watching out for ear fungus....
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I am guilty of selling headphones after only an hour of use. I bought two pairs of Fostex the TH900 and Thxx (mass drop special model). The th900 I returned the day I got them (Amazon) and the thxx I sold the same day online. 

I I just did not like the tuning. Way too much bass and no amount of burn in or system changes were going to fix it. It is hard to demo headphones and they are "cheap" so I buy and change them out ALL the time. 

I am am in the minority here and feel headphones do some things much better than speakers. The major trade off is the soundstage sucks on all headphones so you have to know your priorities. 
I listened to the Fostex 900 at an audio show and really liked them. I have found that satisfaction with headphones has a lot to do with the amplifier that drives them. Listening through a Blue Hawaii headphone amp is a lot different than plugging them into a budget receiver. However, the BHSE amp can costs many times the price of the headphones.
I read a review of several premium headphones by Herb Reichert in Stereophile a few issues back. He tried out several of the big players and was pretty consistent in mentioning how deep into the music this new generation of headphones can be. When he got to a pair of Audioquest Nighthawks, they sounded dull and closed in. He called AQ to find out what's up with 'em and they said the 'Hawks need serious break-in time. So Herb let 'em run in for several days I think. When he put them back on for a listen, they became one of his favorites of the bunch he reviewed, and they were near the bottom of that bunch's price range. 

Ten hours is not nearly enough, and headphone diaphragms have tiny, delicate movements. It stands to reason that just a little bit of suspension stiffness could really make them sound dull and uninvolving.
Johnny- that has been my experience (with break in) and one of the reasons I started this thread.....to see if anyone else noticed a difference after a long break in period.