Devsfan,
As John said, the instructions put the taxpayer on notice you could send it back in this circumstance. For the same reasons that I would not allow a check payable to H & W to be deposited in H's account without direct evidence of her consent, I would send back an ACH that reflected the same situation.
Back to the issue of fraudulent refunds...I spoke to an EDP vendor last week that is considering making any "mismatch" on names a "non post." (I failed to ask if this was on government payments only.) The bank could override or "force post" the item the next day.
That puts the bank on notice when it might have preferred to remain ignorant, but the size and scope of this problem overrules my sympathies. It would help identify "ghost" customers, fraudsters, and, perhaps, spouses attempting to route joint payments to single ownership accounts.
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In this world you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant.