About 24 hours after joining Tinder, Ashley Brincefield, 31, a management specialist for customs in Port Tobacco, Md., began getting creepy messages. Married men propositioned her for sex. Guys lashed out if they didn’t get a reply in a timely fashion. Various men sent naked selfies.

Ms. Brincefield tried blocking them and reporting them to Tinder, but the harassers would just surface under a new screen name, she said. So she decided to take matters into her own hands.

She took screen shots of the offending messages, superimposed them with remarks like “Tinder is not the solution to your marital problems” and uploaded them to her profile as a warning to future matches.

“Don’t mess with me,” Ms. Brincefield said. “I am going to shame them if they send an obnoxious message.”