The USCIS has completed a report titled ""H-1B Benefit Fraud and Compliance Assessment."  The report can be found here.

The USCIS investigated 246 H-1B cases which they state is a statistically valid figure.  Violations could either be fraud or technical. 

Key findings include:

•  Fraud -13.4% of cases,
• Technical Violoation - 7.3% of cases,
• Overall Violation rate - 20.7% of cases.

The following types of violations were found:

• Job location not as approved on LCA or I-129,
• Employee not receiving the prevailing wage,
• Document fraud,
• No Bona Fide Job Offer,
• Job duties differe significantly from those described in the petition and LCA,
• Beneficiary status misrepresentations,
• Beneficiary paid fees only employer permitted to pay.