I've only been going to the range for a few months and seem to still be mostly improving, so it is hard for me to say if I have had a bad day in the accuracy regards yet.
However, I did have a "bad day" experience that I won't quickly forget. I was shooting a SIG P239 9mm and the hot casing ejected, hit me in the face and went right down between my face (just to the outside of my eye) and my safety glasses and stuck there. I must have looked hilarious trying to get those things off my face fast. In the process I even knocked the ear muffs off. One thing that I had read is that in a real stressful situation you won't notice things like how loud the bang is from a gun going off. While this isn't something I have experienced, I did notice after I lost the muffs and was trying to stop the burning that the guns around me didn't seem all that loud. Strange how that works.
Yesterday we were at the range and a hot casing went down the front of my wife's shirt and burned her good. I told her she was lucky that it didn't stick in her undergarments or should would have flashed everyone trying to get rid of it.