This does not match my experience. I've interview many candidates with github profiles that looked active who couldn't code their way out of a wet paper bag.
What's worse is by reading their code on github, I will already form an opinion (sometimes very negative) before I even meet the person!
I've especially noticed that these developer bootcamps that are rising in popularity produce a lot of github cruft.
You mean they have a "fake" history of github activity? Or just a lot of "activity" but nothing really substantial?
Just having an "active" profile can be achieved by cloning a few repos and writing a few feature requests.
You'd have to read the contents of their history of course, code and communication.
Seeing how they reason about code in issue discussions or pull requests is valuable, even more so than reading the actual code.
You make a good point about negative preconceptions from seeing someone's code. I suppose it's better (or at least no worse) than the negative opinion we may form from seeing someone's grades or previous employer.
What's worse is by reading their code on github, I will already form an opinion (sometimes very negative) before I even meet the person!
I've especially noticed that these developer bootcamps that are rising in popularity produce a lot of github cruft.