My worst gear fail was my own damn fault ( like so many thing tend to be on closer inspection).

Got a great deal on a small tent from a neighborhood yard sale. Light weight, 2 walled, airy, great for me and the pup at an incredible price. Set it up easy peasy, no missing pieces, even had a foot print all for about $10. Too good to be true you cynics ask? This was a neighbor who's son had moved across country who had abandoned a bunch of stuff and didn't want it shipped. She wanted her garage back. I even offered to pay more since I really didn't want to take advantage of a neighbor.

first night on my trip it poured and I realized that the tent was demylenated. Yup- stored wrong and the thing was as water proof as a cotton t shirt! Fortunately I was able to hike back to car and snag my usual heavier but waterproof tent and make up the time. After cursing my damn neighbor for 1/2 a night and a morning I realized she had no idea the tent was damaged and I had to find a mirror to blame that idiot. That tent has since spent happy years as a kids fair weather play tent- well worth the $10.