When I see someone's unparenthesee-ized code and can't figure out what they're trying to do, I reach for my copy of "Practical C Programming" and look it up. That way I'm sure I know what the code actually does, as opposed to what the programmer thought he was trying to do ...
nobody but Cidiots can remember all the precedences so, should I come across a problem in some code where I had to look up the precedences (I can't remember all of them, and thus do not do any such from memory), I'd insert parantheses and compare the generated .hex file to make sure I did not change anything but from Cidiocy to code. That way, next time I come across that place it is clear what is going on.

Depending the precedencees instead of using parantheses is just one more way to make C unreadable.

Erik