JoJo Fletcher's runner-up on her season of "The Bachelorette" can't figure out how Lincoln Adim got on the show, because the screening process probes for past crimes.
We got Robby Hayes Wednesday in Venice and asked if 'Bachelorette' producers need to do better background checks on their contestants ... in light of the fact Adim's sex crime arrest 2 years ago didn't raise any flags.
As we reported ... Adim had been convicted of and sentenced for indecent assault and battery days before Becca Kufrin's season premiered in May. He'd been accused of groping and grinding on a woman during a 2016 cruise. He must now register as a sex offender.
Robby is dumbfounded on how Lincoln slipped through the cracks. He's been through the process, and told us the pointed questions every contestant has to answer ... including the ones about arrests. He says Becca deserved to know about Lincoln and producers need to tighten up the background checks.
We broke the story ... Warner Bros., the studio behind the show, says Lincoln lied through his teeth, and the company that runs background checks missed his arrest.