I push the limits of seeing what is the minimum I can get by with is. So with that I can safely say that all my failures are my own fault in one way or another:
1. Rope failure - using rope rated to 400 pounds.
2. Strap failure when a strap sawed through itself - I think that was using some strap I found in Iraq when I couldn't find something else.
3. Rope failure - using rope rated below the safe margin (500 pounds I think) and it failed just below the knot, where all literature tells you a rope will fail when it does. The cool thing was that the rope had made it about 750 miles at that point. I think if I had spliced that instead of tied it, it might still be working today.
4. Body failure from friction with stuff in my pocket when trying to make a hammock out of material lighter than 1.1.
5. Body failure from a design idea I had: foot and shoulder pockets to make a short hammock feel longer. It worked for a few nights but eventually gave out at the joint of the footbox on the side I normally sat on when using it as a couch (and it was very uncomfortable that way BTW). It happened at night, on the trail, during a rainstorm, over a piece of unlevel ground - so I spent the rest of the night trying to stay dry and get some semblance of sleep. So design failure.
6. A friend trashed a Hennessy of mine by hanging it to where his butt kept scraping the ground and he didn't fix that issue. I don't know the details because it was one of those things where you loan someone something and then don't even hear from a guy for about a year, and when you do he is handing you a screwed up piece of gear. It failed across the body and you could tell he had been doing that for a while because there was a great deal of sign of damage across the butt area where it had scraped back and forth for a long time before something finally gave. I credit that one to being too lazy to get up and fix something that should have been corrected right away and then changing how he tied the hammock so it wouldn't do that again.
I've never had a hammock fail that was designed properly and used as directed.