Have you ever been the Shaliach Tzibbur in Shul? One thing I have noticed is that acting in that role is like being a referee in sports [li'havdil!] - you can't win. You are either too slow or too fast, you sing too much or not enough, the nusach isn't right, you didn't pronounce a word correctly etc. etc. All this for FREE! What a deal:)!
May'se that I heard from the Rebbe Shlita who heard it [if I am not mistaken] from a person present:
Rav Moshe Feinstein was davening in his Yeshiva on the Lower East Side. The Shaliach Tzibbur said the shir shel yom as is our custom. The problem was that he said the wrong day. Hayom yom revi'i on tuesday [for example]. Uh Oh! Reb Moshe heard and proceeded to say the entire tefilla for yom revi'i from beginning to end so as not to embarrass the chazzan.