bootleg adj. inferior, unappealing, worthless. (source: Double-Tongued Dictionary)
Further reading
Old. Elderly. Senior. Why are we so uncomfortable when we talk about reaching a certain point in life? An 82-year-old seeks a more positive term to describe how she feels about her age. And: a linguist helps solve a famous kidnapping case, using the...
Tracy in Beaufort, North Carolina, says her grandmother, aunts, and uncles used to try to calm down an upset or bossy person with Well, don’t get astorperious! You might debubiate! In the work of Zora Neale Hurston and in Harlem Renaissance...
What about bootleg recordings of concerts and jam sessions that are highly prized by fans? Those are considered priceless.
That’s a different, far more common meaning that’s well-covered in dozens of other dictionaries and so is not within the purview of this site.
When my daughter started saying it I thought it sounded stupid because I had never heard it used that way. But then again it’s like saying “bogus” in sort of the same way. Stupid, lame, etc. I’m sick of everything being “ghetto”, most of these kids have never seen a ghetto in their lives.