Merits are not reverted if the post is deleted, so the receiver keeps the received sMerit, and the sender loses it to say. I’ve only seen @Theymos revert sMerit TXs once, in a case of flagrant abuse from a hacked account. Even so, he did post that abuse could be treated in the same manner if the case was of concern.

Therefore, merit assigned to a post that was later deleted, maintains its accounting implications like any other non-deleted merit. The only thing is that when you look at the merit history on the user profile, both the Sender and the Receiver will have a TX indicating that the merit was given/received on a Deleted Post.

That does not necessarily mean that merit abuse can be hidden from sight by deleting the post. Some forum members monitor the amount of merit that is involved around deleted posts (amount, from user/to user, etc.), surpasing the 120 day limit on the profile, and it is even possible to recover the deleted posts for some.