Yeap, you right. I saw many stories about malware in sold extensions. Also, I've talked with such company, and they offered me a couple of thousands but told me straightforward that want to embed an aggressive advertisement inside. That is completely inappropriate for me because I respect my users.
I also tried to contact with companies with related business and have sent about 15-20 offering emails. But no luck: only a couple responses, which sound like "Thanks, but we are not interested." Others just ignored it.
