For these purposes, I define a "bust" as someone whose career is primarily defined by their inability to live up to their draft status.
Of course, everyone has a different definition of "bust" and that's part of the fun of this exercise, and we obviously are going to be living in a gray area on purpose trying to walk the line.
My example would be someone like Leonard Davis, who was the No. 2 overall pick in 2001, mostly flamed out in Arizona when asked to play tackle but ultimately became a pretty formidable guard with the Cowboys, even if I think his primary legacy is that of a bust.
An example I obviously wouldn't use even if they did "bust" would be Steve Young, because his draft status and his career in Tampa Bay haven't come to define him at all.
Obviously this is all semantics and arbitrary definitions, but it's the offseason folks. Let's get pedantic
Edit: another good example would be Dan Wilkinson, who was like the defensive tackle version of Jadeveon Clowney. Incredibly hyped, was an impactful defender everywhere he went, but still widely remembered as a draft bust