Can you tell me your experience with personal trainers?

I am considering buying a few sessions with a personal trainer and I’m weighing my options. I lead an active lifestyle and have for years, I don’t need help with motivation or with food or diet advice, but I have some health and joint mobility issues and I am hoping to tailor my workouts to be more effective without compromising my well being. This isn’t something that I’ve been able to get from my physical therapists, as they tend to err way too far on the side of caution and I end up with advice that doesn’t suit my lifestyle especially well.

I have heard that a lot of personal trainers can have an agenda or are out to sell supplements/products, and I don’t want to deal with anything like that. I just want someone with professional knowledge to help me create a new workout regimen. Would that be realistic and how would I go about hiring someone to do that if I don’t belong to a gym (and don’t intend to)? Have any of you had personal experience that you can share?