Here are some other problems I've come across with submitted articles that can get them rejected. Problems With Pen Names
If you promote your articles on the various article directories available, you will more than likely find that these allow you to have a username, which you use to login, and one or more pen names, which are shown as the name of the author of the article. Now, I've seen a few problems with these.
The first fault is usually caused when you already have an account at an article directory, then join an article distribution service such as Article Marketer. The submission service will generate you a new account, and sometimes, if the pen name you use with the submission service is the same as one you already have at the directory, you could end up with a blank as the submission services pen name, as the duplicate is declined. This means that the ability of search engines to spider your articles is significantly decreased, as there are no links to "More Articles By" or similar pages. Some directories will decline your article if this is the case.
Next, using your site URL as your pen name is frequently not appreciated either, so don't do it. In addition, many directories will decline articles written by something other than a proper First and Surname person, so, although terms do vary from site to site, it's unlikely that any will object to a pen name of, e.g., "John Smith", whilst will decline or remove articles by "mysitename.com" or "The SEO Guru". Just remain with a standard name, even if it's not your actual name, and you will avoid any problems such as this.
Bad Usage of Article Rewriters
You may not have come across services like these, or you may use something similar without knowing what it is. There are several different versions around, but what they all have in common is that they are designed to take an article, and make a number of different versions of it. The differences may be only small, but the idea is to create a variety of "different" articles to avoid duplicate content filters.
Now, there is nothing wrong with doing this, but there are wrong ways of doing it. If the spinner replaces words or phrases with variations, for example, "In the beginning" could also be phrased as "To start with", after doing this for an article and producing a number of variants, read each one through to make sure they still make sense. It's quite easy to produce gibberish if you don't, and most decent article directories don't like to publish gibberish. If an article needs tweaking, do so manually. Far better to make sure you spend a bit of time now on the article, then having to fix it after rejection.
The next problem is if you generate a batch of 20 different articles, submit each article to a different site. Therefore, 20 articles to 20 directories. Or submit them to groups of sites, one article to 10 sites, the next to another 10 etc. Do not submit all 20 versions to one site. They'll probably get rejected, and you may get your account deleted for irritating the site owner.
Submission terms, and what an article directory or site will approve or reject do change, sometimes quite substantially, from directory to directory, but if you are cautious, you'll get less articles declined.