They have software that could detect certain language used in listings and pick up those listings. Ebay would have to look at the listings individually and determine whether the listing is allowed or not, but you have to remember that any listings that are allowed to run to completion make money for ebay, both in the original listing fees as well as in FVF. Ebay doens't have the incentive to remove everything. They only remove enough to give the appearance of wanting to have a safe site.
Shoot! I have to remember to do a buy it now when trying to sell illegal items!