Sorry, somehow I missed your comment ... yes, that's correct, they don't diagnose, they clean. Although the woman we were talking to prior to the cleaning said that if they notice something obviously not right during cleaning, they would let us know that a vet's visit is advisable.
I'm really not sure how they do it, but I do appreciate that they would not have the pet's focus if the owners were present to observe. Aiden wasn't the least bit uneasy around her afterwards, so I took that as a pretty good indication that he didn't mind how he was handled at all.
And yeah, lab puppies do like to chew and try to eat everything, don't they? I'm not sure how that would go ...