I had an old pair of Koss headphones (nice medium-big cans, circumaural) that were my absolute favorite in the world. But eventually, after like 3-4 years, they started breaking down. The leather-ette stuff on the earcups started shredding and flaking.. the plastic holders (for lack of a better word) of the size adjusters completely broke off (duct taped back on).. Just started falling apart.
This is actually what sent me on my headphone journey.. Being used to such relatively good sound (Koss has a pretty good rep, especially with their phenominal KSC 75), I found many other cans lacking. Couple years later, after getting my Senn HD 202s (not nearly as good, but better than many), here I am.