"I don't know of any difference," says Gary Malin, CEO of residential brokerage firm Citi Habitats Inc. "You just make sure they qualify. I haven't seen any major shift in philosophy. Building owners are looking to protect themselves in the same way they always have."

With regard to more thorough background checks that might root out suspicious behavior, "I haven't seen any of that. I don't think it plays any role," Malin says. "They look at the client on paper and as long as the client meets their requirements, they're happy. It's almost a science. And an annual income of 40 times the rent with no credit problems is typically what they're looking for. They say 'let me plug in my information and see if this client meets my requirements.' A tenant's a tenant and if they qualify, they qualify."

Rather than looking for evidence of criminal activity, New York City building managers are making extra sure that tenants who haven't moved in yet still have their jobs, according to Insignia Residential Group Inc. senior vice president Lawrence Vitelli. "For people whose applications were submitted prior to September 11, some building owners have had the tenant's financial data resubmitted based on potential financial changes subsequent to the trade center disaster."