A while ago I speculated that the reason why so many scientists find critics of evolution [ahem] less-than-completely honest may be a difference in background and culture. Scientists, particularly research scientists, when they're arguing for a hypothesis against a competing hypothesis, don't gain an advantage by distorting or mischaracterizing their target; rather, if you try to shoot down an alternative by mischaracterizing it, disinterested observers will be more inclined to note your mischaracterization than be convinced by the force of your rhetoric. In fact, if you want to take on the established wisdom, you're pretty much compelled to start with an accurate and untendentious summary of the established wisdom first. This is something it often takes us a while to learn. When I was a grad. student, I often wondered why my research advisor trimmed out the more extravagant rhetorical flourishes in my manuscript drafts, and often added mention of inconvenient facts I omitted. Att he time, I thought it was a 'don't rock the boat' approach, but of course she was just displaying scientific maturity.
In contrast, many IDers come from a very different background. Johnson is a lawyer, where the style of argumentation is almost exactly opposite - you find a few small apparent inconsistencies in a large body of evidence, and work them to death, ignoring what the overall body of the evidence shows. Dembski is a philosopher by training - philosophers work by trying to find inconsistent consequences of a premise, and if a premise leads to a contradiction, they've won. Even those IDers who are biologists usually have little research experience. Behe's an exception, and I think most of us find Behe the least offensive of them. though it appears he's starting to pick up bad habits.
So thence the quote mining. Scientists start by presenting the case against their own argument. Anti-evolutionists see this as an opportunity, grabbing that part of he argument, stripping off the context or any indication why it was being presented, and say 'aha!'.