>>14747752First tip, never put anything in air quotes. Unless you have some NPC that puts things in air quotes a lot, and if you do then kill him off eventually.
Pretty much what the others have said. If it's in the dungeon and it's currently populated, there is bound to be a few intentional pit falls like the classic arrow traps or literal pit falls. If these monsters aren't sentient, intelligent, and particularly dexterous then it wouldn't make sense to have elaborate of clever traps nearby unless they were left there by previous inhabitants, and by now they are almost sure to be set off already.
An already sprung trap can be a nice feature though. It gives a dated feel to the dungeon and let's the players know to be on the look out for more. As for in the ghost town, you should probably keep traps away from there. Unless these monsters are guarding these items in the old houses and could logically set them up, it wouldn't make sense for them to be there. Accidents should only be as a result of poor decisions or rolls by the player and should be spontaneous, not planned. Keep in mind that a poor decision isn't one where the player goes somewhere unnecessary or examines unimportant things. If the players aren't heading for the plot, then move the plot to where they are heading.
In short, wing it. Don't be afraid to pull a cliche encounter and don't try to force scripted events. Don't bother with the details of the dungeons layout, just make all paths point to the objective. Get used to making things up as you go as it is the essence of a good GM.