Here's how I see it when a contest announces a later deadline for submissions:
1. The obvious. They didn't receive enough quality submissions.
Keep in mind that their reputation is based upon what they publish as a result of contest entries. So if they extend the deadline in order to obtain better material, is that so wrong?
2. They received fewer entries than expected.
Contests like to grow over time. Each year since I started the FundsforWriters Essay Contest, the submissions have grown in number. That number is representative of a contest's success in reaching the masses - the talented writers out there. If last year brought in 325 entries and this year, a week before the deadline, they've only received 150, something went awry. The contest doesn't want it known that the numbers dropped, so they extend the deadline.
3. They need more money to cover prize money.
This reason isn't as common as one might think, but I'm sure it happens. Let's say a journal promotes a $1,000 prize and publication for an author. The entry fee is $15. The first prize alone means 67 entries. Consider the cost of publication and paying a judge . . . maybe advertising. Even in the world of the arts, budgets are a factor.
4. Crisis management.
You never know if something happened that sabotaged the event. Maybe the ads didn't make it in time. Maybe the judge got sick or backed out. A sponsor may have backed out. What if the online entry form was down for a week prohibiting entries?
Here are a few credible contests that extended their deadlines this month:
Annual Writer's Digest Competition - WD waived the extra $5 late fee to submit by May 20.
Victoria Writer's Society - The contest entry deadline has been extended to May 31 for submissions of poetry, fiction or creative non-fiction. All residents of Vancouver Island and the Gulf Islands may enter.
Oklahoma Geneological Society Story Contest - The stories may be historically or ethnically important, humorous, or just plain interesting. Deadline extended to May 30, 2011.
Asian American Writers Workshop Short Story Contest - Extended to June 3, 2011. Winning story gets a $1,000 prize and publication in Hyphen.
So, you can look at deadline extensions as tricks by the sponsor or an opportunity for you. Who knows? You might be the type of writing they weren't able to find before the original deadline.