If ignorant Buddhists give money to monks to "make merit" then I guess they deserve what they get — demerit. What a pity though that their devotion is misdirected!
How could giving what is not allowable for monks be a meritorious deed?
In my opinion, giving money to bhikkhus or sāmaṇeras is the demeritorious deed of adhamma dāna
— giving that which corrupts the morality of others, like giving alcohol, drugs, weapons, or sexual favours.
Giving money to eight-precept nuns (thilashins) or white robed lay followers (anāgārika) is a meritorious deed, since they are permitted to accept and make use of money.