We have all done it! We manage to get what we believe to the perfect link. The kind of link that either takes AGES to acquire or by some other magical reason. You then get tempted to right-click, “NoDofollow” to find the link is nofollow for one reason or another and then you feel yourself dying inside a little.
When a link is “nofollowed,” the link is rendered useless in terms of SEO. Which means all your hard work going into getting the link was for nothing in terms of rankings, which makes you want to pull the face above.