I had an experience this morning (2011) which really bothered me. During laining, the בעל קריאה, instead of וְקַרְנֵי רְאֵם קַרְנָיו, said וּקַרְנֵי**. Gasp! No, the real gasp was the chorus of know-betters who shouted the completely unnecessary correction. I had to go over to someone to make sure I had really heard right but sure enough, that is what went down. When will people learn?
**The truth is that by now, I am actually not 100% sure if that was the actual "mistake." It's probably because of what is said in the גמרא סנהדרין כ"ט: כל מילי דכדי לא דכירי אינשי - a person does not remember words of nothingness.