Would the rest of the fleet be aware of what kind of crap Spock has pulled, though? Would Starfleet publicize the events of "The Menagerie" and "Amok Time", among other episodes? Obviously there would be rumors, since people were involved indirectly in some events (the computer tech that tried to stop Spock in the Starbase 11 computer center, or Commodore Mendez's secretary), but would many people in or out of the service learn of these transgressions? I don't think so. So maybe that's why he's still "the best".
Being a quasi military service, I would guess each ship's incidents would be classified. Its not like today's Twitter/Facebook culture, where people cannot stop talking about crap no one wanted to know. In Starfleet--including Starbase 11, we should assume Miss Piper, the computer technician and anyone else was sworn to secrecy for the sake of Starfleet--even Federation security, so Spock's reputation remained perfect.
I think the only exception would be disasters in the nature of that seen with the Intrepid, Constellation, Defiant
. Disasters should become general Starfleet knowledge, since each incident would pose the same dangers to everyone else patroling the galaxy.