A competitor of mine has appeared out of nowhere with various different websites targetting slightly different keywords but all are in the same industry. They don't have as many links as me, the site structure and code is truly awful (multiple H1's on same page, tables for non-tabular data etc...) yet they outperform mine and many of my other competitors. It's a long story but I know someone who knows the people who run these sites and from what I can gather they are using black hat techniques. But that is all I know and I would like to find out more so I can report them.