Autechre at the Metro in Chicago about 6-7 years ago. The Metro has no seating, but a sloped floor instead. I'm only 5'2", so the best place for me to see anything was to stand in the back. However, the place was SO filled with cigarette smoke, I don't think I could have lasted more than an hour back there. I've got terrible allergies, and can normally handle going to clubs, but this place seemed to have no ventilation whatsoever! So, my friend & I managed to squeeze our way near the front of the stage where the air was better, but there was speaker in the way of my view.
Then I had some a**hole who insisted on dancing all over the place, constantly bumping into me, while at the same time chain smoked and almost burnt me with his cigarette!
If that wasn't bad enough, I had to stand in that same spot for 4 straight hours! That's right...it turned out not being just an Autechre concert (as I thought), but some "dance party" with other performers as well. I'm not sure how it was advertised, but the tickets only said "Autechre" and the show was to start at 10PM.
Autechre didn't appear on stage until a little past midnight and played til 2AM. Up until that time, the music pretty much sucked to be quite honest. At least I could SEE Autechre because their setup was really close to the front of the stage. However, there still wasn't a nice view of the gear, no visuals or even fancy lighting. All they did was twiddle knobs while drinking beer and smoking cigarettes. At least their music was good, but damn...that was one of the longest nights of my life!