If preapproval letters from certain lenders are routinely unreliable, real estate agents tend to suggest that homebuyers apply for a mortgage with a different lender, according to new research by Campbell Surveys, based on a national survey sponsored by Inside Mortgage Finance Publications. “Agents are sometimes skeptical of mortgage providers selected without their consultation,” said Tom Popik, research director of Campbell Surveys. Before working with a potential homebuyer, real estate agents largely prefer...