To suggest that scientists funded by oil companies are doing "bad science" is nothing more than an
ad hominem attack. If research is funded by an organization with a stake in the matter such that it would like to see the research come out a certain way, that might be sufficient reason to question the work more closely, but at bottom, the validity of science is not based in any way on the motives of those doing the research, but the ability of others to verify the results produced.
The fact of the matter is that a great deal of research is conducted by someone who wants to see the results come out a certain way. I would venture to guess that most research is conducted by someone who has proposed a theory after observing a perceived regularity with a purpose to the research of gathering data to support the theory. Obviously, such a researcher hopes that the research will support the theory. That's precisely why it's important that results be repeatable.
It's my impression that the biggest threat, generally, to the reliability of scientific research is not the person who willfully skews results for neferious purposes, but the well-intentioned researcher who is unconsciously influenced by a desire to prove a proposed theory.
Those who would sacrifice an essential liberty for a temporary security will lose both, and deserve neither. -- Benjamin Franklin