Recruiter spam has no correlation with expertise but more with your online profiles. Take linked in for example, when I had my real experience there (technologies used, etc) I got spammed a lot, but since changing all my profile to just contain the basic info (worked at X in year Y) just so I can connect with past workers, I get maybe 1-2 linked in spam emails a month. I assume if you have (or had since some recruiters scrape and store) filled your details in a job site (monster, cwjobs, etc) before, that rate will be a lot higher than if you just have a tech blog. Again, no relation with expertise, just online profile