I never really worried too much about the radar, (don't like, don't read, yanno?) but I do like to leave the potentially explicit details out so that readers can make their own assumptions.
For instance, there's a scene in my maybe-comic Meager Cure where Ripley, the Ladette Wrench Wench
who's spent years traveling the South alone, is shocked to discover just how naive 11-year-old Farren is about, er, the birds and the bees. Ripley reassures Farren's guardian, Del, that she'll explain everything in an honest, gentle way, and takes Farren outside their RV to talk to her. Del watches them through the window but, unable to hear what they're saying, is more than a little confounded by Ripley's wild, theatrical gestures. She flails her arms, repeatedly pounds her fist into the table, and gives a dramatic 'spider-like' twitching with her fingers: all with a livid, slightly horrified expression. Farren returns looking very confused and a little frightened, but Del thinks better of asking her exactly what Ripley said.
Of course, we have no earthly idea what Ripley was talking about or if it was even obscene to begin with; but her bizarre kinetics imply, to most people, that she either knows absolutely nothing about sex, or that she knows way
too much to be describing to a kid. Either way, the Noodle Incident
quality makes it funny. So I often avoid explicitly detailing the 'unsavory' conversations or actions, not because I'm afraid of showing them, but because it's usually a lot more amusing to let people guess about them on their own.