First check and see if there are any settings within the DBMS to change that can cause it to not write the bum data to begin with.
If that brings no joy, are the same characters extant in each and every file? If so, determine what they are or if there are always precisely the same number, read the file in as binary into a character array and delete those characters. Then either process the file from memory or rewrite it back out in uncorrupt form and use importdata or csvread or the like.