Evolutionists interpret evidence based on their preconceptions

Claim

The conclusions of scientists are based on their preconceptions. They prove only what they assume.

Oard, Michael J., 2003. Are polar ice sheets only 4500 years old? Impact 361, p. iv. [1]
Gitt, Werner, 1993. Did God Use Evolution?, p. 18

The arrogant hypocrisy of this charge cannot be overstated; every Creationist religiously adheres to a specific Biblical preconception, and flatly refuses to accept any conclusion which conflicts with said preconception. If Creationists honestly believed that there was anything wrong with "prov[ing] what they assume", they wouldn't be Creationists!
To a certain degree, every person is hindered by personal blind spots from uncovering certain truths. But since different people have different blind spots, they can point them out to each other. This is one of the principles of science. If scientists had relevant blind spots creationists don't have, creationists could point them out. But creationists can't find any factual oversights. All they have to say is botched in one way or another.
This argument ignores the sheer mass of evidence supporting the theory of evolution. Many different interpretations are possible when there are only a few data points, but as more evidence is discovered the range of plausible alternatives becomes narrower.
Scientists prove nothing, they find good explanations using scientific methods.
Scientists rely upon scientific evidence, which exists regardless of their preconceptions.
The primary utility of science is its ability to prove that which is not known, let alone assumed. The claim is patently false.

Genuine But Insignificant Cause (creationists can't point out any things scientists have overlooked)
Tu quoque
Circumstantial Ad Hominem