40 years of carpet cleaning and too many years as a landlord, as well as my time as a trainer/supplier have taught me a few things about animal odor:
1. The pet owner has unrealistic expectations. Nothing can be done as long as the "polluter" still remains. Working that issue through with a pet owner takes a unique level of tact and diplomacy. All you need to do is see how many of us regular posters love our own pets to understand this difficult issue with our customers feelings. The easiest odor jobs (from a human relationship point of view) are those where you are hired/referred by landlords, realtors, and banks.
2. Cleaner unrealistic expectations. Most people want a "super product" that can be sprayed from the surface or added to the cleaner. If you aren't willing and able to remove carpet and cushion, don't call yourself a pet odor specialist.
Regarding Mike's comment about overpriced products: I'd rather see a "cheap" or not the most "high tech" product used where it can contact the source of the odor than the most expensive product spritzed on the surface of the carpet.
3. Some carpet's are "terminal patients". If more than 20% of the carpet is contaminated (and I think even 20% may be too high), its rarely economical to attempt to save the carpet. The cost of material and labor is such at times like this that sealing the floor and replacing carpet, cushion and tackstrip is a more sensible idea.
All that crap they taught you in class is just a way to sell you over priced chemicals.
I guess somewhere in there you can point at some suppliers and trainers who sell products and create unrealistic expectations. But it wasn't my 40 years of experience that got my property rentable after abuse from pets and incontient people. Nor did that experience get me through all of our cleaning company odor problems.
Most of it came from going to a class and using some expensive products the right way.