Worst Concerts You Have Attended ??

I just left a remark about a favorite band of mine back in the day - April Wine - that I saw in concert and was disappointed. Could have been that it was an off night for them, or maybe they were never good in concert. Maybe the lead guitarist had too much to drink? April Wine was not the worst, however. I remember Neil Young in the 1990's who was on his one-man acoustic show type of tour that many artists were taking advantage of (perhaps for financial reasons) during that time. While a friend of I had near front row seats at Desert Sky Pavilion (now Ak-Chin) in Pheonix, the crowd was just roused up into a frenzy by the warm-up band (James) and here comes Neil and his guitar/harmonica. Wow, what a sonic letdown. I remember getting up and leaving and feeling Neil's glaring eyes on us as we ushered out. I think, to this day, he probably still remembers me. We all can remember the great live concerts we attended, but what were the worst and why?
This might shock a few folks but it was a Van Morrison show in New Jersey in the late 80’s, he played a medley of his songs for an hour, he’d start a song, sing a line or two, then roll into another one, it was clear the songs that had meant a lot to me, meant nothing to him any longer. In my mind, if you think your own songs aren’t worth the time and effort to sing them, I’m not going to take the time and effort to listen to them. 
Worst Bob dylan in glasgow 2004. Played most the gig with back to audience. Session muso's staring at Bob trying to work out what he was playing and where he was going
Lazy disrespectful and working to pay off a tax bill. 
Still have his music on sacd and vinyl just the person at that time was rubbish. 

Best gigs - John Prine Cambridge folk festival followed by old Crow medicine show in early years... Energy, interaction and perfection. Manu dibangu at Ronnie Scott's london
Pink Martini at Wolf Trap about six years ago... the sound was terrible.. and the way they choose to play different country’s national hits was so funny.. it was so obvious how it divide the crowd on groups who were interested and not.
However the one I really liked was ’13 Depeche Mode at Jiffy Lube Center VA... superior sound and energetic, fantastic atmosphere. 
Deadhead the one time I saw Van was in 1970 at my college. He was drunk off his butt, but still managed to put on a pretty decent show. His material was pretty new to him at the time, so he apparently hadn’t gotten jaded yet. He was living nearby in Woodstock, NY then, and likely stopped off at his local tavern before the show for a few, or maybe quite a few, beers.
Saw Van Morrison once.  Pure torture.  He came across as a proper pompous, tedious little twat.

As a teen I saw (I believe) Deep Purple's last ever gig in Liverpool.  Spinal Tap really nailed that era.   Tedious solos.   Tommy Bolin could hardly stand up.  I think he died a week later.