I have written a manuscript but cannot find someone to help edit it, but I want to submit to a good conference. So can I pay an unacquainted professor to help revising my paper? Thanks!
Yes you can pay someone to edit your work. It doesn't matter that it is a professor or not. But a professor might rather want to become a co-author than a paid editor. If the other person contributes content it might be a more valid thing to do.
You would need to acknowledge such help in any case, I think.
I think it will be very hard to find anyone who'll take you up on your offer.
In some cases professors are contractually limited in the amount of outside consultation work they may perform (I think what you're suggesting falls under that). Unless you're offering a really large sum of money, you probably cannot match the amount of money that professors can get from companies. In addition, professors' true currency is credit (though money is a wonderful incentive!). Spending two weeks consulting for Google is worth more than just the money; it's a line on their CV saying that they consulted for Google.
In addition, what you're suggesting may come off as scammy to some people - if I were to get an email offering me a large sum of money for editing a paper, I would most likely chalk it off to some online scam and ignore it.
Your best bet is most likely to be convince a professor that your paper is worth the time and become a coauthor.
If you simply offer a collaboration I think you may have a chance. For example, does this work stem from some applied problem? Academics are often interested in applying their work on real problems. Do you have access to data that may be shareable with a university? Do you offer resources/contacts in industry that might be useful? If any of these apply it would significantly boost your chances.
If you're just looking for someone that understands the academic jargon, try looking for a graduate student in a related field. Do any of your friends go to graduate school and work in a related discipline?