From the Model Mayhem FAQ:
Why was I denied?
First off, we have to tell you some good news: even though you might have been denied, you get two more chances to submit your profile for review!
When you are denied, you should receive an email that lists all of the reasosn why your profile was denied. The most likely reason is that you simply did not meet our membership requirements. If that is the case, all you need to do is carefully review the requirements and update your profile and submit again!
In some cases, if your profile is denied there may be other issues with your profile that go against our site rules or membership requirements. If you do not understand why you were denied you are always welcome to contact us and ask.