There is a difference between a screw up by a singer, and a malfunction of equipment.
At times, it is difficult for the lay person to know what exactly the problem was, and obviously, then the artist gets blamed, whether wrongly so or not.
Divas 2012 was a clear-cut case of Adam not being able to hear himself. He was singing about a quarter tone beneath the melody, which clearly indicates he could not hear, because good luck trying to do that on purpose, not that anyone would want to. Adam even sang somewhere during the performance that he could not hear. Eventually, after a minute or so the sound came in, and he immediately corrected. Adam did the best he could with the situation.
There is nothing he could have done to fix that. So this one does not count.
I have no idea, whether Adele's situation this weekend was similar or not, and quite frankly don't care.
But about Adam I do care. There are very few bum notes, or even pitchy sounding notes with Adam, in hundreds of live performances, given that Glamberts will record and listen to everything he ever does. I cannot think of any other singer who has this kind of consistency in his vocal performances that Adam has. Maybe in classical music, but not in pop.
There were the infamous AMAs which were pitchy, because he was frantically trying to keep up with the choreography, but they were not as off, as many fans and others have since then always claimed. Then there were a few bum notes during the Kiev QAL concert, one high one in particular. Other than that, you will have to start scratching the bottom of the barrel, tbh.
Some folks count Mad World 1, but I have never agreed with that assessment. He slightly corrects one note, but the steps itself, he sang that way on purpose, and I love it. Never agreed with people who called that off. Diva2012 does not count, not his fault...and then I am running out of ideas what could be there. That is an incredible consistency. A beast of a singer, as has been said before.
Comparisons to Adele, on any technical level - no contest. It's like comparing him to KA. People are just confused, that's all. And moths fly to the light or whatever they perceive to be the light. It's just the way it is. It won't change.
Jist means that we are a more exclusive club, I guess. As long as it is a growing one, and it is, I am fine with it.