When you're looking at in-home care agencies, start by looking into whether there's thoughtful supervision of the caregiving staff. If the person you're caring for has medical issues, for example, there should be nursing oversight of some sort -- someone available for the staff to call with questions and to provide training and oversight in recognizing symptoms of distress and in managing conditions. Even if your loved one doesn't have health issues right now, you might well need this in the future.
Also, ask about how the caregiving staff document what they're seeing in the course of their daily work. In-home care aides should take notes and keep records, and the agency should have no qualms about giving you that information when you ask for it.
Don't be afraid to ask lots of questions, particularly open-ended ones rather than those that can be answered with a simple "yes" or "no." Some examples:
What's your hiring and training process?
What kinds of background checks do you perform?
What's your procedure if a caregiver doesn't show up on time?
How do you handle it if the caregiver doesn't get along with the client?
How do you monitor your staff's performance?
How do you know your people are where they're supposed to be at the right time?
Some agencies closely monitor their aides and have them clock in and out by telephone so they know when they arrive and leave; others won't know an aide is repeatedly late unless the client reports it.
I also encourage families to talk directly with the owner -- and to steer away from any agency where the owner isn't personally involved. Even an agency that's part of a franchise tends to be very good if it's owner-operated. Ask whether the individual aides are employees or contractors, and ask about the agency's hiring end employment practices. Do they try to meet their employee's needs in terms of giving them full-time work if that's what they want? If so, the aides are much more likely to be happy in their work and not leave.
It's also good to find out how they train the staff. If an agency is owned by a nurse, she may train her staff in some simple medical procedures. Some places will only take people who've been trained and certified as CNAs (certified nursing assistants), while others look for more mature people who may not have that certificate but may have more experience and commitment to the job. My preference is for older, more mature caregivers who have a desire to help others and are doing this job out of real concern, not just because they need to do something and this was the job that was available.