Like most of these arguments, it mostly hinges on semantics. What do you really mean by "cheating"?
Legally: Cheating is something that you could be arrested and/or viably prosecuted for. Shot-taking probably won't count, HC won't count, but card marking would.
Morally: Cheating is something that crosses someone's moral line, which is vastly different among people. For some people, card counting is "cheating", since the casino explicitly does not permit it.
Socially: Cheating could be defined as something you wouldn't think of doing when playing a friendly game, for example with friends at low/zero stakes. If you wouldn't do it there, then perhaps it's cheating.
Personally, I stick with the legal definition, since it's best-defined, and most relevant to an AP.