I've recently discovered a couple of completely irrelevant and spammy links directly to out homepage. The link is completely unrelated to the anchor text, blog post and the blog site in general which it is on. It's a wrestling site and the whole blog post appears spammy and hard to read with a link to our site which sells poker cards randomly placed within the anchor text "for". I can only assume this is an attempt by a competitor to add spammy links to our site to decrease our rankings- I can't think of any other reason this would happen? But perhaps someone could enlighten me if I'm missing something?