What happens if an author acknowledges a potential anonymous referee in the paper? Let's say that you thank Professor X in your paper that you will submit to a Journal Y for providing you some insightful comments. It is never possible to know but let's assume that Professor X is the anonymous referee for your paper. This is possible since you make a list of potential referees (this is quite common for some journals). 

What would be the reaction of an editor?
As an editor in both computer science and biology, I would generally consider a person listed in the acknowledgements to be involved enough to have a conflict of interest, and therefore would not invite them to be a reviewer. This is a heuristic, not an absolute rule. 

It is also worth noting that I usually solicit a review from precisely one of the recommended reviewers, since recommended reviewers are often "close" in the network of the authors, and I want to have more independent perspectives as well.  It's still worth listing multiple recommended reviewers, since some may be unavailable, but it's not useful (for editors like me) to make a very extensive list.