It could be some of both I guess. In my opinion the "h" word is overused as a quick and easy "gotcha" and it typically doesn't really provide much insight into the substantive issues.
My primary concern is that the use of dark money channels appears to make it easier for foreign entities to influence the elections in the U.S. It's not difficult to imagine a foreign entity sending a not so subtle message to an elected official "If you don't back arms sales to country X, you'll get hit with millions of $ worth of negative ads in the next election cycle." (or some other such influence)
I'll concede that I have not investigated the legal issues in detail, but the government should be able to regulate foreign money without running afoul of the First Amendment concerns underlying the Citizens United decision (i.e. I can't see how foreign entities have a First Amendment right to express political speech in U.S. elections).
What is the law in Canada with regards to campaign contributions, political ads, etc.?