It is unethical. Makes our entire industry look bad. It works, but do you really want to run your business in this manner? Also, what if the homeowner doesn't want the "pre-treatment". You gonna clean with just emulsifier, or just water or what? What a scam.
Those of you who think you must do business in this manner please take it from me you DO NOT. I went to an estimate today, both carpet and tile cleaning. I measured the areas, gave her a price, talked about the process and what I was going to do and handed her the estimate. She was impressed, and gave me the job. Then she showed me a STACK of advertisements from other carpet and tile cleaners, all using the bait and switch crap. She had been calling all of them to get pricing. None of them would come out to her house to bid like I did, and none of them quoted anything close to what I quoted. I not only got the job, I got it for a heck of a lot more than those screwballs.
When I do the job I will back up my promises, give her her money's worth, and get her to call her friends to recommend me because of it. Now THAT is how it's done.