Of the 100+ runs I've had in the game, I've only claimed victory 37 times (and only once on normal). I have a lot of fail stories, especially with the new AE content (my first encounter with hacking ended that run). Also, I never send help when it comes to giant alien spiders: I've lost more crew than I can count to those things. It also took a long time before I'd try using boarding parties after my first attempts ended with a) the crew dying on an airless drone (oops), or b) the crew getting lost because the ship either jumped away or I'd forget to turn off auto firing.
I have a strong fear of solar flares: I've lost more ships than I care to remember from beacons too close to stars. On my first go at the AE update, my second jump put me too close to a star and the enemy hacked my shields and killed my weapons with the first volley. They boarded my ship and everything caught fire. Eventually, everyone suffocated and the enemy ship burned to a crisp: my one lone crew member had to make a mad dash for the O2 system, but he died just before he got across the depressurized part of the ship.
Once, I ran out of fuel and the rebel fleet caught up to me (this was late in the game, too: sector 5 or 6) and the ship attacking me was completely invulnerable to my attacks just as I was safe from it. Realizing I was stuck with no way out, I simply vented my ship and put everyone out of their misery. In a worst case scenario, I'll usually kill my own crew and/or drop the shields rather than let it drag on.
Often, I'll have systems damaged, ioned, or get caught in an electrical storm and for whatever reason they won't get powered back up once they are restored and I won't notice until it's too late. I don't mind when the RNG or the enemy ships/tactics overpower me, but I hate when I lose because I did something stupid. Nothing worse than that moment of 'oops, forgot to turn the shields back on to full strength' just as the enemy fires and nothing you can do will save the ship.
captcha: point blank. Damn right.