I saw Iron Maiden in the late 80's, GnR opened for them. Axel was so hammered and kept slurring his words and messing up the lyrics, it was just awful. Sadly to say I was quite drunk as well and most of the concert is just a blur, which really sux because Iron Maiden was one of my favorite bands at that time and I don't remember much of their set at all
After that I mostly stayed sober for the concerts I went to.