I bought "The Mothers of Invention - Freak Out" in July of 1966 and became a Zappa listener for my entire life. Frank's music was always interesting and so perfectly rehearsed there was never a mistake.
If you saw Frank in person, you would learn that he was the conductor of his "Evil Little Orchestra" and not the star performer. The musicians never took their eyes off of him because he would improvise something new in the middle of a piece as the concert was as much a free-form event as a totally rehearsed performance. The musicians were so good, well-rehearsed, and understood the music completely so that the slightest hand gesture or nod from Frank could take the entire group through a new transition into another piece.
For those who think "Don't Eat the Yellow Snow," or "Montana" with the pygmy ponies and dental floss bushes are examples of why Frank shouldn't be taken seriously - I would suggest getting a copy of "The Yellow Shark." Frank was one of the featured composers along with John Cage, Karlheinz Stockhausen, and Alexander Knaifel at the Frankfurt Festival in Frankfurt, Germany.
The Yellow Shark was the last album he released and the piece was performed live by the Ensemble Modern at the Frankfurt Festival. The audience gave the Yellow Shark and Frank Zappa a 20-minute standing ovation.
You don't get that by being an average musician.