The dating app, Tinder, is being infected by spam campaigns advertising prostitutes, webcam porn and hook-up sites, according to security firm Symantec.
The campaigns are believed to be connected to affiliate programmes offering spammers money for enticing new members to join the sites.
Satnam Narang, security response manager at Symantec, said: "One year ago, we warned users about one of the first instances of adult webcam spam on the up and coming mobile dating application Tinder.
"Now, a year later, we have observed a number of different spam campaigns using fake profiles to flirt with users of the service."
Campaigns vary in style despite having a common purpose, with a messaging script previously used to push the game Castle Clash said to have been reused to promote webcam porn site Slut Roulette.
But "the overwhelming majority of spam" in recent months has come from raunchy profile pictures overlaid with URLs linking users to prostitutes and prices for various services, allowing spammers to evade filters that scan biographies to flag dodgy profiles, according to the security firm.
"Historically, these image overlays contained a lot of information. Now, each overlay is shorter and straight to the point," Narang added.
Symantec reports that one site called blamcams received 500,000 clicks between the end of January and mid April of this year due to a campaign, but it has been unable to measure success more widely.
"Depending on the offers given by the affiliate program and the number of successful conversions of leads, this particular spammer likely earned quite a bit of money," Narang said.
Rosette Pambakian, vice president of communications at Tinder, said: "We've had a long running spam deletion and prevention initiative in place but last week we rolled out a major technical solution to our current spam issue, which should result in measurably less spam and bots than prior.
"We've already noticed a significant decrease. We also have safety tips on our website about how to detect and avoid spammers."