I've never watched a Bond movie but I've been listening to the BBC Radio adaptations while working and cleaning and I'm coming to the conclusion that in spite of his public school education and being such a highly regarded member of Secret Service that he's rather dim.
He's always falling into blatant traps. Drinking drugged coffee in a villain's home, why would you eat or drink anything there?! not questioning a random Dr wanting to give him a vaccination at the airport, falling for Rosa's nonsense and failing to spot that Nash was clearly suspect. I'm just finishing From Russia, with Love so I'm sure that there's more to come. It's a bit worrying that he's supposedly one of the Secret Service's finest.
And yes I know that it's fiction.