This is a very common problem and I solved it in a very simple way: one account for playing, experimenting, testing and enjoying, and another for showing off. This is not fundamentally different to how people treat HN accounts.
If someone's GitHub profile is a mess, mixing experiments, serious work, goofy stuff, etc. as a result of their multiple uses of it (it's a _tool_ per se), that's up to them and it's up to no one to say "well, that doesn't look very professional to me, does it? your worth doesn't look great here".
But for me, experimental work is fine - I use github for conversation items.
But that's not necessarily a portfolio per se (something _really_ curated for that purpose, which is something specific). If it says so on the GitHub profile page "Portfolio", so be it.
And the recruiter is perfectly fine looking at it, but only for what it is.
What I'm rather aware of, is the pressure/mandate for everyone in the industry to showcase themselves, while that's not a relevant proxy for their fit to this or any job posting.
Sure there are people in the industry making themselves visible through github, twitter and whatnot, and some of these are also excellent. But that's only a tiny piece of the crowd that's available for hire.
This is my Github too; part of me thinks I should finally arse myself, remove unused repos, and build a portfolio with some example projects of how I build software (hopefully allowing me to skip a technical interview assignment), and maybe build some libraries for various purposes. Doesn't have to be anything unique.
I mean my CV is impressive (according to recruiters / employers), but it's a high level overview of projects I've been involved in, it doesn't really boil down to my individual achievements because projects are generally team efforts.
I do believe this is the danger of judging someone by CV alone though; just because they were a part of a project, doesn't mean they were big contributors to it. I've seen plenty of people who do one small commit per week and call it a day. There's always the one team member who gets carried by the rest of the team, just like in school. (childish as it might be, I do believe managers should review individual team members' contributions and to let people go if they're only along for the ride.)