I have done it. When you are a dealer tech and a vehicle comes in with a brake pulsation that is covered under warranty you machine the rotors and use the same pads. Of course if the pads were in bad shape replacement would be recommended. I found the pads were in good shape 99.9 percent of the time.
When I bought my car it had a pulsation, car had 95k on it, pads were Toyota pads put on at 60k. I am 135k now with no issues and it's looking like I might make it to 160k on same pads.
I found no reason to replace them, they have functioned perfectly and continue to do so. Of course I'm the type that takes everything apart every year or two and cleans and lubes everything.
I still have the new pads in the box I didn't use.
If pads are grooved, starting to delaminate from the backing or are rusty I would replace them.
Key words that apply to an answer to your question... ok? can? should? Anything is ok if you rationalize it... you can in fact reuse the brake pad... you'd be better off matching new brake pads to new rotors.
Unless the pads are nearly new, I have a policy that if I can afford it and the work exceeds the cost/value of the used high-wear parts, I'd replace the parts. Brake jobs are an expensive hassle and the pads are a very small expense in the job. And bad pads might screw up the rotors or the rest of the job. I'd opt to replace the pads.
Brakes are a hassle; jack up the car, pull off the wheel, unpack the brake pads, maybe bleed the systems, etc. I don't want to have to re-do it.
If it's a simple job or an expensive non-wear part, I'd just leave it on. Let's say you have to remove a old but good working $100 battery to get to something else to repair it. I'd reinstall the used battery since it's expensive and still has a lot of life. It's simple to replace it as needed.
I just got rotors for the Escape. Replaced the pads last year with the calipers then the rotors warped so they pulsate now. I’m not going to put new brake pads on just do the rotors and sand the pads slightly.
If the pads only have a few thousand miles on them, I'd do it. It depends on how much "meat" is left. I have a friend who did front brakes on his wife's car, and said the rotors "looked good." About 6k miles later she was complaining of the brakes pulsating after he did rear brakes and rotors, which were shot. He asked if I would have a look and help him this time. I had a look at the front brakes and rotors and suggested replacing the rotors, we salvaged the pads, pulsation is gone. I cleaned the pads and gave them a very light sanding. This was done over a year ago.