"high-end criminals" isn't unusual. Certainly not to these British eyes. If you Google for "high end criminals" even without the hyphen, about half of the results use the hyphenated version.
The other things you point out encourage me to share your opinion, however.
The problem is context, a common issue with tracking things with Google Trends in particular. Tracking programming language usage with it, for example, has been a nightmare ("ruby" and "python" having far too many meanings, but few write "ruby programming").
"high end" has more uses than "high-end." For example, "I bought a car at the high end of my budget." In that case, "high-end" wouldn't make sense. In "datacenters have been targeted by high-end criminals," however, "high-end" is a compound adjective.
Alternatively, you could drop the hyphen and/or form an entirely new word: "highend." The word "highend" doesn't seem to have caught on yet, though. I suspect that's because "upmarket" covers the same meaning already and is less susceptible to these morphological mishaps.
(On seeing what OS X had to suggest as a correction for "highend," it suggested both "high end" and "high-end.")
That's a good one, another poster above suggested something similar. I believe that HN'ers would play fair in something like this.
On the other hand that isn't proof of anything, but I think the changes are higher that someone will own up that didn't do it to throw sand in the eyes of the searchers than the reverse.
But then again, maybe I'm a sucker and I believe that people in general are honest and trustworthy. So far that seems to me to be a better assumption than the reverse.
