This is what I don't get about all those "oy vey remembuh the shoah!" stories. They're all improbable or so convoluted that the method of execution resembles a Rube Goldberg machine.
For example, in this case – why bother shooting someone through a secret backdoor? They're going to die; it's not like you need to worry about them warning the other prisoners after you've shot them. Just lead them into a soundproof room (the room would need to be soundproofed anyway so the prisoners wouldn't hear the sound of the gunshot) and shoot them there. And for that matter, why bother shooting them one at a time? If you're going to kill them all (or at least a large portion of them) anyways, just select all the ones you want to kill, take all of them into a room, put them against a wall and shoot them at once. It's far more efficient than just shooting them one after the other, and the increased efficiency makes it less likely that the other prisoners will figure out what's going on, as they won't have time to wonder why their numbers are slowly dwindling and why the people taken to be "examined" aren't coming back out.
But instead we're lead to believe that each Jew was individually lead into some super secret chamber, examined for no reason whatsoever, taken into another room for some reason, and shot through a secret trap door.
If the story of the Holocaust was along the lines of, say, the Armenian genocide, I'd be much more inclined to believe it. The Armenian genocide was how a genocide would be carried out – quick and efficient, with the minimum expenditure of resources. No fancy trap door shooting, no overcomplicated gas chambers (a bullet is cheaper and faster), no magic ovens that can incinerate a person in five minutes and leave behind no bone fragments. Just force people out into the desert at gunpoint, shoot the ones that refuse to leave, let nature take care of most of them, and shoot the ones that try to come back.
More importantly, there's post-facto evidence of the Armenian genocide. There are bodies. With the Holocaust, apparently six gorillian Jews were killed, but somehow no mass graves have ever been exhumed – the bodies just disappeared. So then they claim that the bodies were all incinerated, despite the fact that even if you assume all the furnaces were burning 24/7 with no downtime due to repairs or fuel shortages (which by the end of the war were so severe that front-line Panzer divisions were immobile more often than not), they still couldn't have burned anywhere near six million bodies even if they had been doing so from the very start of the war to the very end (in reality some camps weren't operational until after the war started, most Jews weren't rounded up until still later, and many of the camps were liberated before the war's end). Not to mention that bodies burned in furnaces leave behind fragments of bone and teeth, none of which have been found.
Then of course you have the question of why the Nazis would waste boatloads of fuel burning Jews when their primary concern throughout the whole war was acquiring greater sources of the stuff – so much so that Hitler diverted divisions from the assault on Moscow to attempt to secure the Soviets' Caucasus oil supplies – and when they had such great shortages that their own army units often had no fuel. Yet for some reason they continued to waste millions upon millions of gallons of it burning Jews when, again, a bullet to the back of the head is faster (it takes hours to burn a body) and works just as well – dead from being shot is just as dead from gassing/burning.
Then there are the "personal accounts," which are so fantastic to defy all common sense. For whatever reason the Nazis turned Jews into lampshades and soap; they had a literal rollercoaster to dump the Jews into magic massive furnaces (neither the furnaces nor the rollercoaster o' death have been found, of course). They masturbated Jews in fantastical semen extracting machines… for some reason. It all sounds like a plot from a bad, low budget '50s movie, where the goal is to portray the bad guy as comically evil as possible. I'm surprised they didn't claim the Nazis watched each gassing from behind a massive one-way mirror while simultaneously masturbating and twirling their mustaches, to be honest.
