Some people prefer PC known/unknown, depending on the sorts of activities they want to do on the account with a pet. Just being honest about the visibility/activity is fine. If the pet is being watched/stalked, transferring always has a risk of being reported/frozen. That's just an unavoidable part of life. Sorry. You can have strategies to mitigate this somewhat, but there's nothing ever 100% safe, which is why we don't allow claims like that to be made here. Everyone working in the blackmarket needs to be aware of the potential consequences. Even if you were a legit player moving a pet that is legitly yours, you still run that risk.
I'll also take this opportunity to give a friendly reminder that if you do go ahead and try to sell, keep all mention of circumstances out of it. This includes about losing interest/quitting, needing money etc.