A cable box I got from a Comcast installer had a roach colony living in it. I didn't notice it until I saw the front panel LED (for time and channel display) "flickering". I took a closer look and saw something crawling behind the plastic.
"No...it couldn't be!"
I peered down through the vents of box and saw more movement until finally a german cockroach crawled out of one of the vent slots and onto the top of the cable box.
Needless to say, I quickly unhooked the box and threw it into a trash bag. I called up the installer (who was a contractor for Comcast, btw) and demanded a new one.
So yeah. I had always heard that bugs and roaches like the heat being generated by the internal PSU of electronic devices. I've never seen roaches chillin' on a 360 power brick though.