Depends on how technical the bowler is. Most wouldn't care, but for me, it delays the roll of the ball as the coverstock is not reading the lane the whole time.
I ran an online pro shop a few years back and I had a disclaimer on the 'shoe' page.....
I provided a fitment guide and warned the buyer bears the responsibility for a correct shoe size.
However, each shop owner could decide whether or not they looked after their customer in this...