A while ago, I stumbled upon Butz's "The Hoax of the Twentieth Century" and thought to myself "heh, let me have a look at what this neo-nazi conspiracy crackpot says and have a laugh". However, I was surprised by the reasonable arguments and the complete lack of neo-nazism* I found. Many of these arguments I could not answer. Of course, I am no expert, but one would expect the evidence to be readily available on the net if it is truly "overwhelming". I could not find very much. Instead, I found a lot of rhetoric and fallacious arguments, and plenty of irrelevant photos and unclear or anonymous witness testimonies.
* I assumed Holocaust-deniers were neo-nazis, and I don't expect much from them since I think nazis are fanatical murderous bastards. However, if there were no gas chambers, they are no worse than the murderous bastards among the Soviets or British colonialists. I would still strongly disagree with neo-nazis (there seem to be plenty here, too

I did find a good, comprehensive site, http://www.nizkor.org/, but it was not free from misleading rhetoric either. I'll have to study it in detail though, and read a few of the main pro-Holocaust books like Shermer's and Pressac's (not easy to get) before I'll make up my mind. This is too serious a topic to approach lightly. However, the fact that the alleged masses of evidence are not readily available, and the hot air and rhetoric I came across, not to mention the downright totalitarian suppression of critical thinking, is very worrying.
So much for my introduction. The question I want to ask is the following:
Revisionists point out that there is little or no forensic evidence, no documents, and plenty of holes in witness testimonies. However, how much evidence can we reasonably expect?
The lack of documents is a serious issue, but they could perhaps be destroyed. There are also some, like the Jaeger report, that do seem to indicate mass extermination. But this is certainly a major problem for the mainstream theory.
However, what about forensic evidence? How much could we realistically find? How easy is is to find mass graves? Obviously in places like Treblinka some MUST be found if the story is true, but what of, say, Auschwitz? Have attempts to find them been made? Can we expect them to succeed immediately? Once graves are found, is it possible to determine how the people died and who they were? Is it reasonable to request solid forensic proof here?
Regarding forensic evidence on the remains of the alleged gas chambers, I don't know enough about the science to be able to tell what is reasonable to expect.
Regarding witnesses, can we reasonably expect that there are witnesses who went through this whole horrible traumatic experience (even for the Nazis, at least at the trial) and are still able to give a testimony with NO holes in it? Testimonies that describe in detail the workings of the gas chambers where they (allegedly) saw thousands of people die? Can we expect this much from them?
It's clear what conclusive evidence would be here. However, can we realistically expect to get it, even if the mainstream theory is true? Is it reasonable to expect that there is a single indubitable piece of evidence or witness despite the chaos and horror and destruction of the war and the Nazi regime?
Finally, is it reasonable to expect to have a theory on any aspect of the war in which no holes can be poked and no weaknesses identified, regardless of whether it is true? I personally have not found such a theory in my somewhat extensive reading on the military aspects of the war.
In other words, historical theories are conjectures, and in analyzing the chaos of war even more guesswork and uncertainty is involved. If gas chambers existed, what is the reasonable minimum of evidence we would expect to find, and would this satisfy the revisionist criteria for proof?