SURE, BUT HOW WAS THE SEX? A mattress that ensures a good night’s sleep may not guarantee the best naked romp. An extra-firm mattress may offer plenty of bounce (fun!) but no traction (not fun). Some memory foam users complain that during sex, the partner on the bottom sinks into the mattress, unable to move. And, because memory and latex foam mattresses are designed not to bounce or move, they make it hard to rock the boat, even when you want to.