They look through your electronics, also your laptop. Didn't take them long to clear me though. But I'm a white Scandinavian and my most recent posts to Facebook were about board games and concerts and most of my mails were in Danish or spam about video games.
I mean, they would probably still have cleared me if they had access to the full story, I'm not that much of a deviant. But take the board game nights as an example. A few of my friends smoke weed at those, and even though I haven't done that for 10 years, it's not something I'd want to be associated with on a social media site that a government trawls, so I make sure to keep that part out of the pictures.
On the other hand if you lack these things that everyone is expected to have, they become suspicious.