I have a bunch..
As far as mainstream acts go, three automatically come to mind. My first concert was Breaking benjamin, Staind, 3 doors down and some crappy opener ("No address" was their name, I think). Breaking benjamin was just awkwardly loud. Wasn't exactly the best first band to see live cause it messed with my ears at first, to the point where I was starting to get nervous. Their notes were muddy and inaudible at times because of the volume that was beyond overly bassy. They seemed like good sports though.
Same show, 3 doors down was just annoying. I didn't really care much for their music to begin with. In between songs, the frontman would just ramble on to the crowd for several minutes, aimlessly. Also, before at least 3 or 4 of their songs, he would say "this one is my very favorite one to play". I don't know if he was half drunk or what, but it just seemed like he was tripping over his own sentences at times. If he had said "one of my favorites to play", I probably wouldn't have thought twice about it.
Last one was Puddle of mudd. All the other bands they played with were great, and I think they did put on a decent show. But once again, the frontman...
He started to go off in the middle of a couple of the songs, "singing" things like "pussy pussy pussy pussy, pussy pussy pussy all night long" over and over and over again for several minutes. I mean, I could have seen how that would appeal to some but I was just thinking "*** is this guy doing?!" it was just annoying after a few minutes, but he just kept on going!!
The last show I was ever at was "Dan deacon experience with special guests Lightning bolt". I was just getting into the noisy stuff and figured "well, if they are with LB, then they must be pretty interesting". Couldn't have been more wrong... I learned quite fast that EDM is not my thing that night. Maybe it would have been if my mind had been altered in some way that night, like the other memebers of the crowd more than likely were. But all it was for me was a few bearded nerds jumping around like they were 5 years old to giddy and super fast electronic beats for an hour and a half straight. It was like one long beat with a couple of silent breaks in between. And their openers were local acts in the same vein which were equally as dreadful to sit through for me at least.
Alot of the local "bands" here are just as bad as anywhere else of course. I too am guilty of being a part of a few that were just...blegh. But thankfully I was not even close to being a part of the two worst I have ever seen. One was a band from the opposing HS playing at our talent show. They were poorly EQed, especially the bass player...he was entirely low end.. literally no mids or highs at all. They had two guitarists, both with half or full stacks and a keyboard player with a tiny amp. Needless to say, you couldn't hear a damn thing that key player was doing. They played this corny mixture of pop punk, emo and a bit of some kind of "_____core" in there. The dudes in this band were equally as odd as they were arrogant as well.
And last but not least, was a "band" that the jock type kids had formed just to play the talent show a few years earlier. I don't know how else to describe their performance other than just an utter mess. I realise that playing is all in good fun, but they put so much emphasis on the fun part that everything was just kind of out of wack. I heard they had been drinking and smoking in their cars not long before hand, so this might have something to do with it. Singer was practically talking the lyrics, and was holding a guitar the entire time pretending to strum yet couldn't play at all. There was a sax player who was going a bit overboard if I remember correctly. The kid on bass looked like he was the only one putting a bit of real effort in. It looked like they were having fun, but to the crowd it was like a joke. Most of the people around me and my friends watching were talking some serious trash and laughing and yelling at them... a few of my friends included.