The 'DWTS' alum explained on her "Sex, Lies, and Spray Tans" podcast that celebs who come on the dancing competition often get involved with their dance partners because the way it's set up is for two people to truly bond and get close ... physically and mentally.

Because stars are constantly rehearsing with their partners -- which involves a lot of close contact and vulnerability -- Cheryl says it's a recipe for love ... which can be bad if you come in taken, because your relationship might be doomed.

Cheryl says getting close to one another on the show is inevitable ... adding, "These celebrities are so vulnerable because in order to succeed, you have to strip it all down. And that alone? I bet you most of these married celebrities have never even done that with their [partners]!"

When asked what's the golden rule for those eyeing up a spot on dancefloor, the show's seasoned vet quipped, "Be single if you do 'Dancing With the Stars.' That's all, I'm saying."

Cheryl confirmed she had 3 "showmances" of her own, including one with ex-footie star Chad Ochocinco Johnson -- but insisted they were purely about lust, especially since she didn't think the romances could ever translate IRL.

Cheryl's spark with ex-hubby Matthew Lawrence was also ignited through 'DWTS' when his bro, Joey Lawrence, appeared on the show. Of course, there've been plenty of other examples of celebs hooking up on 'DWTS,' including Mauricio Umansky and Emma Slater.