Define reliable.
To me, the government is relying on their figures to try to calm citizens down. Hence their obvious attempt to reduce the numbers as much as possible.
Also, to me, Big Business likes to rely on this methodology because it helps mask the effects of outsourcing, transferring industry, calling someone "full-time" when they only work 28 hours a week, and increasing part-time and temp (contract) workers instead of hiring full-timers. It also makes it seem like the paltry increases in job opportunities are having a greater effect than they really are.
Reliable figures should include all possible sources of competition for jobs. For example, we hear complaints about immigrants and their effect on the job market, but where are these figures in relationship to unemployment? They do compete for jobs, regardless if many of those jobs aren't what "citizens" typically desire. The mere competition created by their willingness to work for ANY small amount "under the table" reduces availability for citizens who are willing to work for minimum wage service jobs. There are also many students who "work under the table," as well as those listed as "marginally attached" or "disgusted." Every "under the table" job means one less available for real employment. Those are just a few examples, and still don't address the potential workers who for whatever reason are not "currently seeking work."
Until these kinds of things are part of the overall calculations we really won't have "reliable figures," just blatant propaganda.