This is the usual trick of some merits abusers, they delete the post after sending the merits, and then everyone does not know the quality of this post, so you have no evidence to accuse the abuse.
I tend to treat 99% of deleted posts with the merit gets as abuse. Because 99% of the time, high quality posts will not be deleted.
If I find someone(Usually those has only 1 merit) has merit, but I can't find the post when it gets merit, I think that merit is suspicious.