I don't think the merit sources are selling merit. I've had a few requests to sell, but I just delete the mail, and put the member on ignore.
Actually, I think there is phenomenon buying and selling merit, sir. I joined a group and there is buy merits in it. But the number of no more because they are afraid of being banned. It is done in a secret way and the little one interested. When the number is small, no one noticed. 1,2 merit, then, can no one noticed. But when several times and not clear, then we can find out. But, above all, articles must have quality, then it deserves to be 1 merit. So I think before the sale merit, the buyer had to have a post of sufficient quality to sell it. thanks sir