As many gay men have before him, Mr. Clark chose to live in a city rather than the sort of small town where he was raised in the hope that Kansas City would provide a greater margin of tolerance and also of safety. Even in nearby Independence, Mo., he said, “if you kiss your partner in a restaurant, you could find somebody waiting for you outside when you went to the car.”

But haven’t things changed radically from the days when lesbians and gay men were considered pariahs, before gay marriage initiatives became ballot issues, before Ellen DeGeneres was picked to host the Oscars, and cable TV staples like “Queer Eye for the Straight Guy” made a competitive sport of group hugs?

In some senses and in certain places, apparently, they have. The landscape of acceptance, as the Snickers commercial inadvertently illustrated, is constantly shifting — broadening in one place and contracting somewhere else. The country in which anti-gay advocates like the Rev. Fred Phelps once drew headlines for picketing Matthew Shepard’s funeral and preaching what was called “a Day-Glo vision of hatred” can seem very far away at times from the laissez-faire place in which an estimated 70 percent of Americans say they know someone who is gay.

“We don’t administrate public displays of affection,” said Andrew Shields, World Church Secretary of the Community of Christ, a Christian evangelical church with headquarters in Independence. “Homosexuality is still in discussion in our church. But our denominational point of view is that we uphold the worth of all persons, and there is no controversy on whether people have a right to express themselves.”

The tectonics of attitude are shifting in subtle ways that are geographic, psychic and also generational, suggested Katherine M. Franke, a lesbian who teaches law and is a director of the Center for the Study of Law and Culture at Columbia University. “I’ve been attacked on the street and called all sorts of names” for kissing a female partner in public, Professor Franke said. “The reception our affection used to generate was violence and hatred,” she added. “What I’ve found in the last five years is that my girlfriend and I get smiles from straight couples, especially younger people. Now there’s almost this aggressive sense of ‘Let me tell you how terrific we think that is.’ ”

Image Roger Padilha of Manhattan says he is unafraid to hug and kiss his boyfriend in public. Credit... Nicholas Roberts for The New York Times

Yet gay-bashing still occurs routinely, Mr. Patton of the Anti-Violence Project said, even in neighborhoods like Chelsea in Manhattan, where the sight of two men kissing on the street can hardly be considered a frighten-the-horses proposition. “In January some men were leaving a bar in Chelsea,” saying goodbye with a kiss, Mr. Patton said. “One friend got into a taxi and then a car behind the taxi stopped and some guys jumped out and beat up the other two.” One victim of the attack, which is under investigation by the police department’s Hate Crimes Task Force, was bruised and shaken. The second had a broken jaw.