I lurk mostly because, well, I haven't had much to say. My sites have always been fairly stable with each update, but that seems to have changed with penguin.
I do have links from a lot of places including from social media, forums, etc. because that's the nature of the beast for my business content. And yes, I've seen that I've had some scraper sites hit up my content as well.
Seeing a decrease in traffic at this time of the year isn't unusual as my traffic pattern is most definitely cyclical, but when I look at keywords that I've long placed well for (and still do in other search engines), I am seeing some pretty significant drops in google.
I wouldn't use any tool that Google gives us to disavow unwanted links because there isn't enough time in the day to get my work done much less ferret out supposed unwanted google links.