The lights of the Casino Royal Adult Theatre glistened on rainslicked streets as Allen Terrell, part-time minister, and Valcour Pierre, part-time business student, loitered in the doorway trying to look friendly.

"Have you been counted in the 1980 census?" Pierre asked one customer. The man hurried inside without answering.

Foot soldiers of the U.S. Census Bureau, Terrell and Pierre were out early yesterday morning and late the night before, trying to count the homeless and the transient, the people who might spend the night in an all-night movie house on 14th Street NW.

But they were not about to hear anyone inside.

"Maybe they'd be too absorbed in the plot," ventured Terrell, a well-dressed young man with a shy manner.

Terrell, Pierre and about 50 other census-takers roamed the park benches, jails and flophouses of Washington yesterday. Code-named "M-night" for missions, which were also to be counted yesterday, the effort is part of a nationwide push to ferret out every last American for the 20th decennial head count.

Cities complained during the last census that many poor people were missed. For every person not counted, a local government can lose $150 to $200 in federal grants and a sliver of political power, which is reapportioned according to census data.

The movie house offered slim pickings ("We have a certain clientele here," snifted the box-office lady). So Pierre moved on to a doorway at 1415 H Street NW, where an elderly man wrapped in a burlap bag sat guarding six trunks of possessions strapped to a cart.

"I've been counted," the man insisted.

"Are you sure?" Pierre asked.

"Everybody knows my name," he said.

Pierre, who hones his persuasive powers as a fund-raiser for Dial America, launched into a spiel about how confidential the census is, and how important it is to raise highway funds and the like.

"Go away," the man said, turning his head away. "You talk too much."

Down the street at the Trailways bus station, another team of census-takers was having better luck.

Raymond Bacon, 22 and sporting a black eye, was fresh off a ship and headed to Portsmouth to visit his mother. He had not received a form when they were sent out to 86 million American homes on March 28, because he has no fixed address.

Seated in a row of orange plastic seats he said he was "definitely" pleased to fill one out. "What do you know if you don't have a census?" he asked. "I only wish they'd asked me what are my views on life in general."

What are his views? "Well, we're going through a period of social inadequacy. But in five or six thousand years, that's when you're going to see a change."

Mike Sessions, a management analyst at the Energy Department, was offered the standard 19-question "short form." But with little to do but wait for the bus and listen to Muzak, he asked instead for the 64-question "long form," given randomly to one out of six Americans.

"You've got to be counted," said Sessions. "I'm interested in genealogy and the census is the basic source for tracing roots. Hopefully my posterity will say great-great-grandfather Sessions was counted in the 1980 census."

At the Alcohol Detoxification center, a man with bulging blood-shot eyes was less pleased to submit to the long form. "When were you born?" said the census-taker. The man responded "1952." A few questions later: "Were you born before April 1965 or after?" He answered "After," and promptly fell asleep.

In Fairfax County, six workers sought out transients at two truck weigh-in stations along i-95 and at the local jail. In Arlington and Alexandria, census-takers went to National Airport and a juvenile detention center. Montgomery workers interviewed people at an all-night drug store and along the C&O canal.

As a once-in-a-decade effort, this census had its share of foul-ups. Several missions would not let census-takers in at first because preparations had not been made in advance. D.C. police precincts refused to allow prisoners to be interviewed, but information was gleaned from arrest records.