My experience with PT's has been pretty godawful. Over the past 10 years, I've worked with about 5 of them, and only 1 of them knew half as much as Steve. Most of them seem to come straight off the set of "Work Out" -- in other words, they think their duty is to make you sweat and they don't seem to understand anything but the machines.
I guess if I were to go about interviewing a PT now, the first question I would ask is, "I'm trying to lose xx
pounds. What kind of
exercises would you have me do?" If the PT starts rattling off a bunch of machine
exercises focused on single muscles or joints, e.g. adductors, abductors, glutes, biceps, etc., then there's no need to go any further. If, on the other hand, they start talking about complex muscle
exercises like squats, deadlifts, pullups, presses, rows, etc., then you may have something going.
The next question would be about the weight to use. If the PT recommends "bunny
weights", then there's no need to go any further. If they recommend as much weight as you can handle, then continue with the questions.
Then I would ask them about "toning". If they repeat the BS about toning, which is just another name for spot reducing, then stop. If they tell you something like "as you lose weight, the muscle underneath the
fat will start to be exposed, and that's all toning is," then continue.
Then, since you're a woman, ask about "bulking up." If the PT's answer to that is low weight + high reps, no need to go any further.
Most PT's pay a $300 fee, take a test, and hang out their shingle. Most of them are utterly useless when it comes to keeping you on the right track, because half of what they tell you is wrong.
However, if you can find a good one, then it can be a great experience. I had a good one 8 years ago, and he taught me how to do squats and deadlifts and a lot more. Six months later, he was hired away by the local university to help coach their football team.