This is one of the top categories of consumer complaints filed with the Attorney General's Office each year.
Consumers by the hundreds enter into bad deals, work with unscrupulous companies and simply get ripped off. See the Attorney General's publication Know Your Rights for tips to avoid scams.
If you're having work done on your home, make sure your agreement is in writing. If your contractor doesn't use written agreements, you can draft your own. The Attorney General's worksheet for those doing home repair or remodeling walks you through the information you need to write up an agreement for both parties to sign.