Is the point of view of the person or organization obvious? If there is advertising on the page, is it clear what relationship exists between the author of the material and the advertiser?
Is the purpose of the web site to inform or to broadcast an opinion? What audience is this web site trying to reach?
If a source if trying to sell you something, be critical of any information they offer, as their ultimate purpose is to convince you to buy their product. Financial investment may be as obvious as ads on the web page, or more subtle, like oil companies lobbying for fracking.