I can see her being a bit of liability
It is from "The Goblet of Fire". A Bertha woman got lost and nobody knew where she had gone. And here Sirius characterizes her:
"She was a bit dim, but she had an excellent memory for gossip. It used to get her into a lot of trouble; she never knew when to keep her mouth shut. I can see her being a bit of liability at the Ministry of Magic... maybe that's why Begman didn't bother to look for her so long..."
With "being liable, responsibility, financial obligations, debts" for "liability" the dictionary gives an unexpected interpretation as "disadvantage", the synonym of which is "nuisance".
So, that lady was not being looked for not because she had debts or obligations (what in such case she must have been definitely hunted), but simply because she had been bothering everybody a lot and it was a treat she was not there.
But I can't get the logic of it, how the same word may be used almost in opposite meanings. Any thoughts?