The main character (A) is randomly accosted by some guy, who is allegedly working for some kind of organization aiming to make the city greener, on the street to sign his petition with the main character's name and phone number. Later he gets a call from an unknown number that the payment of his loan is due and that he better pay up soon or else he'll have some goons sent over to beat him up (it's obvious that the petitioner is behind this) but the MC refuses and hangs up on him. Later he gets a call from a friend (B) who says that his co-worker ran into the same situation, except that he was gullible and actually paid the amount and asks MC for help in finding out who's behind all this.
Here's the conversation:
A: gasps ・・・・・・・・・ (probably because he realizes that he fell for the same scam himself)
The bolded やつ is what confuses me. Which person does it refer to here, the scammer or Kenya? I'd assume the former as 性質が悪い usually refers to a person who, as far as I know, is inherently bad in an evil/selfish kinda way whereas Kenya isn't a bad person according to MC's friend but rather just gullible. I've taken a look at the official translation and the sentence was translated as I just can't believe Kenya fell for that. which does seem more natural given the flow of the conversation but now I'm not sure.
Can 性質の悪い人 be interpreted as somebody who's just stupid/gullible but not evil?
As always many thanks in advance for your help!