It may be that they are not tabs at all. You can cast the column to varbinary and look at the ascii code to see what the character(s) are.
SELECT ColA,CAST(colA AS VARBINARY) FROM YourTable
It could also be that the data in the table has some other collation. Japanese, Chinese etc. perhaps? You can see if it has any unexpected collations using this:
SELECT name,collation_name FROM sys.columns WHERE OBJECT_NAME(OBJECT_ID) = 'YourTable'