There are many patches of almost-identical sites.
Some of them are due to many people using the same theme.
Some of them are expired or parked domains, which I reckon should be detected and excluded.
>Some of them are due to many people using the same theme.
Teeming masses of sites using what probably seems to the authors as a fresh, unconventional look but ends up being Yet Another.
Yeah those clusters are interesting. They stand out, so they are the first thing I zoomed in on, then I realized they're all just stock resume sites. Quickly realize the clusters are something to avoid. Turns out to be an effective visualization method.