There are many records that fit into this category for me, but that is mostly due to my own ignorance.
I had picked up a handful of Lionel Hampton lps and they were quickly sent to the basement so my expectations were very low until I checked out The Lionel Hampton Quintet, which was originally a Clef side I believe. This lp is pure joy pressed into 12” of vinyl. One whole side of the record is Lionel, Buddy Rich, Oscar Peterson, Ray Brown and Buddy De Franco just going to town on Flying Home. I played this for a friend who prefers his jazz a little more on the free side of things and his comment was, “They just sound like they are having fun, don’t they.”
Most of the time this happens when I have formed an opinion with out really having listened to, or being completely ignorant of, a particular persons work. Seeing Anita O’Day in the film ~ Jazz On A Summer’s Day was another one of those moments.