Well, sorry for choosing a word you don't agree with. I could have chosen "interesting" instead of decent - it does not change my point.
"'deceptive practices', 'impersonation', or 'extortion'" - this, however, is your interpretation and it is taking it pretty far.
'deceptive practices' - that I can agree with. No matter how you do it, it is deceptive. Then again, a lot of businesses were built with (oh, say Airbnb or Youtube) / use (every cheap airline website) shady practices.
'impersonation' - does not have to be. What if they clearly list that this is not an official X site? If your data is public and crawlable, is it illegal for people to use that information?
'extortion' - does not have to be. Isn't this an equivalent of going to the same business and saying, I did a bit of research on you, then I told 3 people about you and they would love to buy your services. I'll refer them to you if you give me $5. Is this illegal?
If you're being clear that you're just gonna be attempting to relay info, then you're probably OK. The issue is that you'd discover it to be more profitable to lie, and pretend you're the actual business. That way, you're holding their reputation hostage. If they don't pay, those customers feel that the real company just ignored them.
It's not a terrible idea for targeting SMBs that don't have a website, so long you aren't misrepresenting things.
If you want to be a dirtbag, you might as well build one of those "stress tester" sites or something. Sounds easier.