Aren't almost all troves worth it?
The most common wasted trove is probably getting a weapon trove when you already have your endgame weapon, or you're fighting unarmed. It's also completely possible to roll a trove of the right type that has absolutely nothing you need. I remember once getting a jewelry trove once with absolutely zero artefacts. And despite the huge pile of mundane amulets, I was
still missing rMut after that.
So yes. Worthless troves are possible.
On average though, the odds of getting something useful is usually worth risking, unless the requested entry item is particularly rare or actually important to you.