From the e-bay ad:
"As with most bulk-rolled film, the last shot of each roll will not come out properly as it is taped to the spool. "

I have no idea that that means. Perhaps he is using six inches of tape?
My other interpretation is that these are actually half-rolls (18 exposure) and he winds out to 27 on the bulk loader's counter. So he is indicating you won't get the full 27 exposures.