Sometimes, when I read a Spider-Man comic book, I notice that Spidey's Spider-Sense completely fails for no good reason. For example, in ASM #24, Spidey gets taken in by Mysterio posing as a psychoanalyst and nearly reveals his secret identity to him, without his Spider-Sense warning him. That was either Stan Lee's or Steve Ditko's goof.

IMHO, Gerry Conway was particularly bad at it, with his "Spider-Man's Spider-Sense protects him only from his enemies, not his friends" idea that enabled Aunt May to break a vase over Spidey's head (ASM #114) and Professor Warren's Jackal to slash him repeatedly, without warning (ASM #148-49). (Ironically, even though Professor Warren was enough of a "friend" to Peter, notwithstanding his homicidal vendetta against him, not to set off his Spider-Sense in ASM #148, Mary Jane Watson, notwithstanding that she and Peter apparently slept together between ASM #149 and 150, apparently wasn't enough of a "friend" not to set it off at the end of ASM #149 (as Peter's Spider-Sense told him she was in his apartment).) Conway also had Spidey using his Spider-Sense like sonar (to detect the layout of Hammerhead's hideout in ASM #114) and like enhanced hearing (to hear someone on the other end of the telephone line speaking to Hammerhead, also in ASM #114).