The use of corporate resources tends to come up from time to time, as such, where do they stand with regards their use as a source? Should they be accepted as a good reference, anecdotal resource, or on a case by case basis depending upon what is being discussed?
First off, I think it really depends upon the time of information that is being sourced, for example, for factual items such as the memory limits for Windows, I tend to trust the MSDN Library that is curated by Microsoft likewise, I would also trust technical whitepapers to generally reliable although depending upon the topic I would likely want to see a secondary reference to backup the claims.
However, that said, for references where the company appears to have an agenda towards what is being said (e.g. tobacco companies being the canonical example), I would be disinclined to trust the source that is put fourth as it could advance their claims.
In the interest of full disclosure I should start by admitting that I might be slightly biased against corporate resources, but then again, it wasn't too long ago that they told us that smoking is good for you it might not be entirely unwarranted.
I would rephrase your question:
What do we do with sources with a Conflict of Interest (CoI) with their claims?
- Evaluate (explicity, in the answer) the claim versus the CoI: how strong is this conflict? Does this make the source rubbish or is it irrelevant? Would the claiming party benefit at all from a lie/misconception?
- Is there any corroborating (or disproving!) evidence elsewhere? Is this the only source available? If it's the only source then it's possibly, but not automatically important to mention it in an answer.
- Is the fact that companies make such statements relevant? E.g. Shell states that their oil is better than Exxon. This is a strong answer to "Is Shell claiming that their oil is better?", but not so strong to "Is Shell oil better than Exxon?" or "Is Exxon oil better than Shell?". It is, however, possibly interesting if Exxon hasn't challenged Shell on this - not as strong as we would like, ideally, but at times it's as good as it gets!
- Are there any other answers with stronger references? Then avoid.
Most of all, the community (which is made of experts in evaluating factual evidence!) should vote and evaluate such answers on a case by case basis.