Ask HN: How to spot fake or low quality GitHub/public portfolios?

With public portfolio (github/own site etc) becoming more preferable for candidate assessment than plain old resumes, how can HRs without a good tech foundation can assess those wide variety of candidate portfolios and grade them relatively? How can the HRs spot fake and low quality work on the portfolios? Is it even a real problem faced by recruiters?

Or is it that all recruiting is now only through solid referrals and not via public job boards etc?