Very slim to none. A rogue planet would be very cold and totally lifeless, meaning it would emit very feebly indeed in the radio wavelengths. Spotting such bodies is very hard indeed (witness all the trouble they had finding Pluto and that's only at the (relatively) close distance of 39-40 AU.

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You are standing on a 4.5 billion year old complex, self-sustaining organic spacship, which is orbiting a power source a million times larger than your ship. There are 200 billion other power sources, many of them with ships like yours, in your fleet. There are 40 other fleets in the immediate neighbourhood and your entire neighbourhood is moving at two million miles per hour towards an object 150 million light years away. Welcome to life, it's a lot more exciting when you think on larger scales.