Recently, many DP members complained about their SERP ranking drops or unable to find their page in google index. All the blame goes to penalty. Usually, if we get a backlink from a bad neighbourhood side, let's say domain A have 1000s of links on that page and they link to us. We can' control incoming backlinks and even though it is from link farm, we still don't get penalty. But, if we link the link farm site, there are higher chance for us to get penalty. Let say, our site or blog link to domain A (which have 1000s of links on that page and most probably marked as link farm by google). I found a great tool to check this for us, however I'm not so sure it provide the accurate results but it gives a good idea of where our links going. Check your website or blog have linked to any bad neighbourhood: http://www.bad-neighborhood.com/text-link-tool.htm