I have edited a few articles here on Wikipedia over the years. I finally decided to stop doing so anonymously (or not so anonymously with IP address displayed).
Disclosure:
I am a publicist. I will disclose when I contribute to and/or create an article of a client or client's project. While I would never be dishonest, I would obviously be inclined to contribute facts that are biased favorably towards any client I represent even if I was unaware of my bias. For instance, if I were handling a feature film that received mixed reviews and I was submitting 5 for inclusion on that film's page and trying to be unbiased with 1 positive, 1 negative, and 3 mixed reviews, human nature could cause me to submit a "rave" for the positive, 3 positive reviews with a critique here or there as mixed, and a mixed review that was somewhat critical as the negative. It is entirely possible I could do this without realizing I just submitted biased material as it was not my conscious intent. I will endeavor not to do this and if I do so, please give me the benefit of the doubt and correct me so I can become a better editor rather than chastise me. I love and respect Wikipedia's high standards and goals. I would never knowingly compromise them.