Samantha said a big tip-off is if your partner comes home with wet hair – a giveaway that they could've had a shower somewhere.
She also revealed a surprising way some cheaters hide their secret from their partner.
"When they become very anti-cheating – if someone suddenly becomes very sanctimonious and judgmental about people who cheat – I think that's a good sign they're doing it themselves," she said.
Elsewhere in the podcast, co-hosts James Weir, Carla Bignasca and Samantha looked into a crazy new claim about Kate Middleton and put it to the test.
Samantha also revealed a little more about her own love life.
"I've had sex in a police car, that's all I'm saying. That was the best car I had sex in," she said.