In discussing washing salted meat according to Halachah, there is a lengthy discussion about whether and when we can rely on a non-Jew who claims to have done it.
The Tur (Y"D 69:10) says that there is a disagreement between the Smak and the Riva. The Smak says we can rely on their word if they happen to tell us without realizing that they are giving us the information we want to hear, and that we can rely on them if there had been someone entering and exiting, which itself is broken down into two reasons: fear that they might be caught not washing it, and a general assumption that non-Jews are careful about cleanliness. The Riva says we don't rely on their word at all because we can just have a non-Jewish chef taste it and tell us if there's a salty taste.
Later sources discuss further stringencies and leniencies, including a fear that if they know our customs they may be more apt to lie to reassure us. My understanding is that the general rule of thumb we follow is that, for Ashkenazim, if they casually tell us we can rely on them, whereas for Sepharadim, only if there is someone going in and out may they be trusted.
These issues are mentioned with regard to washing salted meat because that was a common issue that people dealt with - having partially prepared meat in the kitchen with non-Jewish servants around. But the bottom-line issues are relevant across the board.
My question is, with regard to bugs in produce, are we allowed to trust non-Jews in places like restaurants, where there is a minimum requirement of cleanliness required by the government, who spot-checks food establishments (similar to entering and exiting), as well as a reputation they want to uphold that their food is clean? Many people eat salads at business lunches that are held in non-Kosher restaurants. Can they rely on the salad being bug-free for these reasons?