No, because you don't want ot get into an infinite regress about figuring out the cost of figuring out the cost to, etc. So you need to have a general policy about when to stop the regress, and ensure that your policy is good in most of the cases you'll actually run into in practice, while acknowledging that it may not be optimal 100% of the time.
Recently, multiple suspicious user accounts were created on Less Wrong. These accounts don't post any content in the forum. Instead, they are used only to send private messages to the existing users.
Many users have received a copy of the same message, but different variants exist, too. Here are the examples I know about. If you have received a different variant, please post it in a comment below this article:
I don't know yet about anyone who replied and got scammed, so this is all based on indirect evidence. If you got scammed, please tell me. If you are ashamed, I can publish your story anonymously. Your story could help other potential victims.
Most likely, the scheme is the following:
(Thanks to ChristianKl for explaining the system in the Open Thread.)
If you replied to the original message and now you are already in the middle of the process, please inform your bank as soon as possible! Even if the step 2 didn't happen yet, so you can still get out without losing money, warning your bank about the scammer could help other potential victims.
Warning: If you have already received a check or a payment confirmation, and someone is asking you to send the overpayment back quickly, do not send anything. The check or the payment confirmation is fake, and the goal is to make you send money before you find out. (Thanks to qsz for explaining.)