Herrmann said the two - James O'Keeffe, who describes himself as a filmmaker activist, and his companion, Hannah Giles - came to Philadelphia ACORN's office on Broad Street near Parrish Street on July 24, claiming to seek help in buying a home.
Herrmann said the couple had made an appointment a day earlier to talk with a staff member about a program for first-time home buyers.
A staff member talked with the couple for a few minutes, Herrmann said. "As soon as they said anything about prostitution, she asked them to leave the office. She told us, and we called the police," he said.
"These people went to a lot of ACORN offices around the country," Herrmann said.
On Thursday, the House voted to deny federal funds for ACORN, three days after the Senate took similar action.
The funding cutoff came amid a conservative-media firestorm prompted by the airing of videos taken by the pair in ACORN offices in New York, Baltimore, Washington, San Diego, and San Bernardino, Calif. Those videos appear to show ACORN workers' telling the pair to avoid mentioning involvement in prostitution.
In response to the legislative action, ACORN chief executive officer Bertha Lewis said in a statement that the organization was disappointed by the House move. She said ACORN has been the target of "a multiyear political assault stemming variously from the Bush White House, Fox News, and other conservative quarters."
Lewis said the funding cutoff would have minimal impact on ACORN: "Fortunately, ACORN derives most of its income from its members and other supporters, so the decision will have little impact on overall operations."
In Philadelphia, Herrmann said the group was planning to hold a "Truth about ACORN" event next Saturday.
"ACORN has been in Philadelphia since the 1970s, and the work we do is dedicated to providing services and helping low- and moderate-income families," Herrmann said.
"The idea that these two people can come into our offices and play . . . tricks and discredit the work the organization has done for a long time by fooling a few employees really is frustrating."
Contact staff writer Vernon Clark at 215-854-5717 or vclark@phillynews.com.