Many times Rabbeim give mussor shmoozes to an audience that they know well and they say things to an audience that they know well. When someone repeats these schmoozes to a different audience they dont translate very well and it backfires .
I dont remmeber all the details, but a big Rav went to a Shiva call of a man who buried his son and said something like how priviledged he was to have had this son for whatever time it was and the father was comforted. Someone nearby heard this and later when to a shiva call under similar circumstances where a man was sitting shiva for his son. Not only was the man not comforted, he made this situation alot worse and people nearby tried to get the man to stop with his “menachem Aveil” and he refused saying he was repeating the Rebbes words.
Just because you heard a schmooze from a Great Rebbe in one situation, doesnt mean you should repeat it in another, It might not translate well and might make things worse