Acknowledgements and reviewer selection For some reason, I was always under the impression that people that are included in the acknowledgement section of paper are not contacted to review your paper because they would be predisposed to give a favourable review. However, after reading the discussion in this question it seems like it is standard to send papers out for review to people in the acknowledgements section if there is not another conflict in place (like being from the same institution, for example). Which is it?

Do editors send a paper out for review to people in the acknowledgements section? Can I suggest a person I acknowledge for helpful comments as a potential reviewer (assuming there aren't other conflicts of interest)? If the field matters then I am interested primarily in mathematics, theoretical computer science, and biology.
The acknowledgement is there to thank people for their help in the work. It is not a place to provide information to the editor on who may have conflicts of interest. You list such persons in a cover letter with an explanation for why there is a conflict. This will make the situation clear to the editor. Persons in the same department will pretty much be excluded by default but if an obvious connection is not present it should be pointed out in a letter. It seems a little odd to thank someone without there being any connection to the work so I would not recommend trying to suggest such a person as potential reviewer. At the same time a person who ha a conflict of interest should decline to review with the excuse that there exists such a conflict. I would say such behaviour is good etiquette and good ethics.

I know there have been instances where a person received a strong reject review on a crap paper by a high-ranking scientist and then used the name in the acknowledgement thanking for input on an earlier version of the manuscript. The manuscript was almost the same but the signal was the high-ranked scientist approved it and so reviewers were unwilling to reject it. Hence the acknowledgement is not a place where a seasoned editor would look for valuable information.