Yes, surveys that most of us might have filled at some time in our life time in some form, may be on the Internet or offline. Most of the time surveys come down to statistics that companies might want to know or show to their customers. I had heard a saying about Surveys a long time back and read it again today on Jeff Durham's article on Cert Cities "statistics don't lie, but statisticians do". From my personal experiences and my experiences that I have heard over the period of time, I know that half of the times company sponsored surveys do tend to lean towards their side or is not the whole part of the story.
Jeff Durham talks about a survey that was conducted by Comptia last year and argues if the figures of the survey match up or if the figures are justifiable. Although the copy of the article is not publicly available (http://www.comptia.org/surveysolutions/roiwhitepaper0903.pdf), I remember reading the article and even complementing the author of the article at one stage (he wrote about his work on the article on the forum). Try to use cache feature of Google or from somewhere and see if you can find the article's copy is cached somewhere). The article mentioned on Return on Investment on Comptia Certifications and how effective Comptia Certified people are and how they reduce the cost of ownership and stuff. I would support Jeff that the figures that are mentioned in the article does not represent the sole fact that the results were solely because of people were Comptia Certified.
I can give few more examples of this, but the point is, are how reliable are company sponsored surveys and should a individual make a blind decision just based on the statistical figures mentioned in such surveys?