For me the worst would have to be a Fender MIM 60's Reissue Strat in Lake Placid Blue. The neck and body were fine but the bridge was unable to be internotated even somewhere near acceptable.
After "working" with the store and Fender for 14 months, Fender took the guitar away to fix it. 6 months later the guitar was returned with the note I had written to the techs still slotted through the strings just as they had received it. I dont even think it was opened and there was no work done on it.
I was told a new neck and bridge had been put on the body, but questioned why the serial number was still the same on the neck and the scratch on the back of the bridge was in exactly the same spot as the old one. I was told the guitar was fine and advised that it was my playing style that made the internotation be so woeful.
Lucky for me the owner of the store played the guitar and noticed things just weren't right with the guitar and replaced it with a new Fender USA Deluxe model after he learned of the events surrounding my guitar. I would never buy a MIM Fender again.
The good news is my new guitar is 100%.