How to tell when exterminator is cheating

We have subterranean termites and from what I've read, the most likely treatment will be boring holes through the slab and injecting a non-repellent type termiticide. I will be calling a few places next week and see what they recommend. A few questions: Can the exterminator dilute the material and use a lower concentration? Can they put less solution into the holes than recommended? How can I tell? What is the best way to tell that I'm getting what I am paying for? Thanks