For whatever else their shortcomings, Google is relentlessly focused on a good customer experience in search. If you are on a guitar site, do you really want to see an ad for knitting supplies? If your business is making sure senior citizens get the right medical workups, do you really want to see links from plumbing supply places?

You need to check those links one by one yourself. There is no other way to do this effectively. Suppose you are getting links from a porn site, for example. Google will not like you. Not one little bit.