I have noticed that if I accidently 'more' or 'cat' or whatever a binary file and the terminal displays unreadable characters, the best thing to do is to 'more' the file again, keep pressing space until the more prompt which says the percentage at the bottom changes back to readable characters and then press 'q' to quit back to the bash prompt. Usually you will only have to press space once or twice and your terminal is fine.
This is the best solution I have figured out and it has worked like a charm for me.