Infallible Sigh-ence

Are the proclamations made by scientists regarding historical evidence valid, accurate accounts of the past? Or are they bad science, using assumptions without weight given to all the empirical evidence relating to facts surrounding the given study which may refute the ultimate aim of that study?
In other words, are scientists only finding the facts they want or are they being truly objective?
Case in point; on a recent fact search I found a website which listed, amongst other things, a short group of "fact" points designed to demonstrate "how we know about past climate."
The first point said:
> "the geological record of carved mountain valleys, scratched bedrock, glacial debris and moraines gives evidence of the past several million years."
I thought this fairly accurate citing the claim that this was merely evidence rather than proven fact. (egos notwithstanding)
Point two:
>Recently, cores have been removed from the ice at Vostok station in antarctica. The longest cores about 2000 meters, sampling layers of ice deposited as early as 160,000 years ago. The ice trapped bubbles of air when it froze.
The ratio of oxygen isotopes in this air indicates the average air temperature at the time the bubble was trapped in the ice. The bubbles also trap atmospheric greenhouse gases that can be measured.
OK! Well, first, not to bash those with degrees too harshly:
I'll assume the core sample librarians have taken into account the Idea that some of those layers may have been made liquid and refrozen over the past 1600 centuries. But did they remember that even frozen ice is still fluid? The importance of that tidbit of knowledge becomes evident over the time span indicated because air bubbles, being much less dense than the ice will continually exert upward pressure and some gases may escape the bonds easier than others. Has this been fully explored?
The Idea that Ice works better than tupperware over the span of thousands of years is, frankly, hard to swallow.
So, the leap from air bubble content to average air temp seems less sure.
By the way, to help with the average air temp question..at the time the air bubbles became trapped, the air temperature was probably at or below 32°F. Just let me say, I didn't need the ratio of oxygen isotopes to arrive at that conclusion.
The point here of course, is that we can't say we "know" so readily. we need to adhere more closely to the scientific method. This has been a thorn in the side of the scientific community for as far back as we care to look.
In defense of the folks that assembled that webpage, there were many more points that all stated the case eloquently and the page as a whole was based in fact.
My point was to demonstrate how easily the facts can be manipulated with a few poorly stated claims.
Now we need to take another look at Al Gores entertainment endeavour in which the real truth was clearly too inconvenient for his cause.
Perhaps there exists a theory as to what his cause could be if not his genuine concern for gods green earth. Judging by his personal consumption tendency concern is not one of Al's strengths.