Service providers have a responsibility to meet their clients' mental and physical needs and so it is never acceptable for them to use clients to meet their own needs, regardless of whether those needs are social, financial, or sexual. I find that people have an easy time with that as long as the elder didn't want the sexual contact. Where confusion arises is when the elder didn't refuse or may have initiated the contact. But we need to have these prohibitions because it is so easy for persons in positions of authority to take advantage of elderly clients. Most licensed professionals would lose their licenses for it.
Many older women are unwilling or perhaps unable to tell others that they've been abused.
Sometimes the signs are very blatant. In a number of cases I've had, the abuse was discovered when a service provider or family member walked into a room and actually witnessed someone sexually assaulting an older person. Others have walked into rooms and seen things that were very suspicious like a caregiver jumping back from the bed and looking upset and worried. Sometimes it is the older person who acts stressed, fearful, or combative when a particular caregiver approaches to bathe or dress them, take them to the bathroom, or care for an injury or wound. That would certainly lead you to suspect that something is wrong and warrants further investigation.