I actually spend quite a lot of time coding in my spare time, be it Project Euler, code katas, messing about in a new language for shits and giggles, doing pluralsight tutorials or hacking on an experiment for my employer's product at night or on a lazy weekend afternoon. None of this is really useful to throw on GitHub, and being penalized for it under the assumption of "not enjoying coding in my spare time" is pretty ludicrous.
Also, I prefer Hg/BitBucket for personal code anyway.
Github (or equivalent) presupposes that you've done some coding that is (1) worth sharing with the public (2) organized enough.
A lot of "learning code" is going to look like crap - the first few thousand lines of code you write when you're learning a new language, a new problem domain, or (!) both at the same time. The fact that it isn't useful for public viewing doesn't make it useless - it was an important part of the learning process. But sharing it with prospective employers is unlikely to be valuable.
Also, I prefer Hg/BitBucket for personal code anyway.