Pins 0 and 1 are TTL level signals. Before attaching to an rs232 interface you must convert the signal to rs232, which involves changing the voltage levels and inverting the signal. A TTL logic 0 is ~10V rs232, and a TTL logic 1 is -10V rs232. (I think the actual ranges for RS232C is somewhere around 9 to 15 and -9 to -15.)
If your bluetooth device expects a true rs232 interface, this is probably your problem. To make it a true rs232 interface you'll need to use something like a MAX232 between the arduino and the bluetooth device.
There are some rs232 variants (RS232F, IIRC) that use TTL voltages but the signal is still inverted. This means you could use a simple TTL inverter (7404) to get the appropriate signal.
-j