A report this week showing rampant foreclosure abuse in San Francisco reflects similar levels of lender fraud and faulty documentation across the United States, say experts and officials who have done studies in other parts of the country. The audit of almost 400 foreclosures in San Francisco found that 84 percent of them appeared to be illegal, according to the study released by the California city. The audit in San Francisco is the most detailed and comprehensive that has been done - but it's likely those numbers are comparable nationally," Diane Thompson, an attorney at the National Consumer Law Center, told Reuters. Across the country from California, Jeff Thingpen, register of deeds in Guildford County, North Carolina, examined 6,100 mortgage documents last year, from loan notes to foreclosure paperwork. Of those documents, created between January 2008 and December 2010, 4,500 showed signature irregularities, a telltale sign of the illegal practice of "robosigning" documents. Robosigning involves the use of bogus documents to force foreclosures without lenders having to scrutinize all the paperwork involved with mortgages. The practice was at the heart of the foreclosure scandal that led to a $25 billion settlement between the U.S. government and five major banks last week.