Escape characters in Oracle dump
As someone who spent 4 years of his life dealing with converting CLOB type data from legacy systems into Oracle, I feel your pain. 

I highly recommend using an Oracle built function, such as REPLACE to go through and scrub all of the garbage characters from CLOB type fields. Additionally, remember that most systems consider a "return" to be a new line and carriage return in unison, so you might have to scrub ascii characters below 33. IIRC the new line/carriage return combo was char(10)char(13). You can easily google a list of of the "invisible" ascii characters, and hunt down the ones you want removed.

HTH.