Unfortunately, there are a lot of people in this country who want to scam you into thinking they have a black belt.
There are also a lot of people who would like to scam you into thinking you can get a legitimate black belt with less than 3 years of study.
Remember, any good reward in life comes after lots of hard work!!!
The Kukkiwon's website (headquarters for the World Tae Kwon Do Federation) has a form for checking the status of black belts that were certified in their system.
You'll need the black belt's date of birth in order to use the form.
http://www.kukkiwon.or.kr/english/new_examination/new_english/pop.jsp
Here are a few links about black belt certification fraud:
Articles:
Black Belts Are Meaningless and a Scam:
http://martial.jessecrouch.com/2009/11/black-belts-are-meaningless-and-scam.html
"Loyalty" Only Factor in Issuing Dan Certificate Through Kukkiwon in US:
http://www.mookas.us/media_view.asp?news_no=1432
Black Belt Prestige:
http://tkdtutor.com/TopicsSidebar/Instructors/BlackBeltPrestige/BlackBeltPrestige01.htm
Forum Posts:
http://www.bullshido.net/forums/showthread.php?t=57988
http://www.defend.net/deluxeforums/korean-martial-arts/7296-boycott-tae-kwon-do-i-hate-wtf-tkd.html
http://www.martialtalk.com/forum/showthread.php?t=29231