One denialist argument is that scientists face tremendous pressure to support the mainstream view of climate change. The argument goes that those who support the mainstream will get the grants while those with skeptic opinions have no prospects for advancement (see this comment thread for an example).
I don't think that matches history - Einstein did pretty well in the world by overturning Newton, and quantum physicists seem to do well as they refute Einstein. Barry Marshall overturned the common belief that stress caused ulcers (a common belief being something different from a well-proven, established consensus) over a period of ten years, and has been showered with rewards since then.
Stephen Johnson, the US Environmental Protection Agency head doing everything he can stop greenhouse gas regulation, will be the next test of this idea when he steps down in 2009. While it's not scientific work of his that benefits the fossil fuel industries, it should demonstrate in general whether they reward people who help them. Talking Points Memo covers the latest from Johnson, delaying making official a finding that they've already been forced to conclude, in order to get "public comment."
The Bush Administration, which promised in the 2000 campaign to regulate carbon dioxide when Al Gore wasn't ready to go that far, has likely succeeded in stopping anything until a better presidency gets installed. We'll see if the fossil fuel industry rewards Johnson as their point man in this effort.