I often see SEOs, webmasters and site owners complaining that their competitors are building spammy links, buying links, doing PBNs and more and yet their competitor ranks well and is doing excellent in the Google results. They say, why shouldn't I do the same thing? Good question but the truth is, you really don't know if those spammy links are helping them.
The links may be helping them, it may be hurting them or more likely, it may not count at all and those efforts may be wasted on your competitors part. You simply can't assume those spammy links are the reason the site is outranking you.
John Mueller of Google responded to such a complaint in the Google Webmaster Help forums explaining all of this. An individual reported all the link spam and John responded:
Thanks for the report, Attila! I believe the team already saw this from the other forum, but thank you for taking the time to put it all together. The tricky part about issues like these is that our algorithms (and the manual webspam team) often take very specific action on links like these; just because the sites are still indexed doesn't mean that they're profiting from those links. In general I'd recommend using the normal webspam report forms for issues like these, it's also fine to send bigger compilations to us directly. I realize it can be frustrating to see these kinds of sites seemingly profit from such spammy tactics, so thanks for your calm post with all the details.
Forum discussion at Google Webmaster Help.