It's pretty tempting to submit PLR articles to article databases. After all, they're keyword rich and ready to go, but there are several negatives to doing this. The primary one is that it makes you look lazy and brands you as part of the herd that's just out to make a buck. Remember, you're not the only one who knows how to Google. Here are a few other reasons NOT to do this--
PLR subscriptions reach many people, so if every Internet marketer submits them to an article directory they will all be deleted for submission of duplicate articles
Duplicate content might come into play, and it is rumored you could see penalties from search engines.
Your readers are looking for value, so at least rewrite the content somewhat to make it unique to your site and use it to the best of your abilty for affiliate sales and establish yourself as an authority.
Article marketing is about branding and using PLR for this will skew the branding that you are working towards.
If readers think you are plagiarizing or copying another site's material, it will devalue your branding, name, link etc. Even if it's not true, it' looks bad.
Article directories refuse duplicate content and may ban you from using their service in the future if you submit something that has already been submitted.
Even with modifications your article from PLR may appear to the be very similar to others that have done the same thing with the same article causing the same reprecussions as if it were exactly the same content.
Think about the PLR process, you pay for the rights to using the PLR, putting it into a free article database is giving it away free for others to use as well, which is breaking the rights agreement of the PLR subscription in most cases.
The most crucial reason above all is that you are not the only person using this article, and it would be more beneficial if used in other ways on your website and in your newsletter compared to what might happen if you submit to a directory.