Update:
One of my better sites was under negative SEO attack these days, I just found that out half an hour ago when I checked some Majestic metrics. I got links from all kinds of pharma and porn sites, my guess is Scrapebox. Note to spammer: You suck at ranking, you even suck at spamming. Grab a shovel and start looking for a job. Traffic is still the same on that site, no drop or increase and it will stay this way.
I have never disawowed anything until today, but whole procedure took me 5 minutes of work and voila here I am. It was probably done by some noob who can't rank shit, so he plays around with Scrapebox. But this is just another thing I'll have to look for when I'll run more successful sites and my guess is that this happens often.
I have started buying links for new sites and I have found some really great sources for them. 10 strong links should do the trick (mixed with some basic backlinks). Right now I have 5 links reserved for one of my sites. Metrics: DA30+/PA35+ and TF15+/CF15+, all with great link profiles.
Will be back when another idiot spams the shit out of any of my sites.
I'm using 5 different themes at the moment, that's the only thing I can tell.