Ask them the success rate for archery hunters for the last five years. Then ask if the percentage they give you is an average for the five years or rate for each year. I would want to know the percentage for each year as one great year can make the success rate look outstanding when they do an average.
I would then ask for contact (references) info from at least ten different hunters that have been there , both successful hunters and those who didn't harvest anything.
A good reputable outfitter should be able to provide you with at least ten references easily.
Be carefull , I've had outfitters provide me with references that just happened to be all locals.