The free online encyclopedia is the fifth most visited website in the world, no wonder marketers are attracted by the possibility to promote customers and their products by creating new entries on purpose or editing old ones.
Such enthusiasm is opposed by editors and readers alike, they feel this approach will damage users and break rules, negatively affecting quality and reliability.
If you ignore the submission guidelines for contributors trying to promote and advertise the following banners will appear progressively on top of your article:
Only show one side of the coin, quietly omitting what’s on the other. This is a violation of the balanced viewpoint policy.
Weasel words everywhere and open endorsement to the subject of this entry. Just like ads do. Not something you would expect from an encyclopedia.
You’ve kept reverting to your biased version of the article in spite of all the warnings you’ve received from editors (you go through four stages before this last message)
Unbeknownst to many, Wikimedia, the foundation behind WP and its sister projects, tried to address the issue in its «Wikipedia for Marketing Communications Professionals» (part of the Bookshelf Project), while it’s still self-assessed at «in development» stage after one year from its last edit, it provides anyway some precious insights:
1) If your organization is big enough to be featured in WP, chances are, at least one of your employees is an experienced Wikipedian, let him/her manage it;
2) You should NOT edit  articles about yourself and your company or product , your personal involvement is supposed to affect your ability to maintain the required NPOV (Neutral Point Of View). If you find factual inaccuracies please contact the editors through the Discussion section of the article or with a direct message, disclose your affiliation and be sure to provide verified data from reliable sources to back what you say;
3) Create a user profile of yourself with public disclosure of who you are and what your affiliations are. Use it for your conversations with other editors, this will help improving transparency and gaining trust from them;
4) Submit pictures of products, executives, facilities, illustrations, or whatever media can be helpful to illustrate the entry about your organization and otherwise hard to find, under the Creative Commons CC-BY-SA license or similar;
5) If the page is removed for a reason compliant with WP guidelines DO NOT attempt to restore or recreate it, it may lead to a ban from future reappearance;
6) Do not expect editors to be forced to comply with your requests, they are unpaid volunteers that may miss the time and resources to, and/or your requests might be unreasonable;
7) Eventually you’ll have to accept negative information about your product, your company not meeting Notability guidelines and whatever else could be out of your direct control. Cope with it.
 The other marketing guides I’ve found online, written by PRs and marketers, seem to happily ignore this warning, it’s a choice that will backfire sooner than expected.
 Editing to remove vandalism (swear words and the like) is allowed, just be sure to add “Vandalism” as the reason to the Edit Summary field of the Edit page.
 Provided they are facts backed by verified sources.