What are the most common link building techniques that have never worked for you?

I constantly see lists of the best practices like X proven linkbuilding methods that WORK, but I always see something that I can't believe works for someone. I know we all have something that works for us and we will not share (at least in public).

But let's share something that's not worth trying, specially if the linked resource is of lower quality.

For me, number one failed method is Broken backlinks. I've never talked to a webmaster in my life that would consider linking to a random website suggested by a random stranger in an email. That's just not happening. I wouldn't do it either.

Do you have any?