Dean Martin is seemingly right for the part of an actor who appears on television as a doctor, such as Kildare or Ben Casey, and then moonlights into the field of psychiatric advice (and perhaps romantic stimulation) for the glamorous dames married to his TV-business associates.But there’s the slip between cup and lip. The slip makes the difference between what might have been mischievous, zesty comedy and what is a sometimes laughable frolic that in a couple of instances is permitted to sink in its quest for sophisticated hilarity. This is unfortunate because a substantial part of Who’s Been Sleeping in My Bed ? plays sparkingly well. Martin is an amiable performer in light comedy and does fine with the material at hand.