A radio signal could be either intentional or unintentional. An unintentional signal being found is extremely unlikely. Radio isn't very useful for interplanetary communication, so the purpose must be local. But every civilization would have the desire to conserve energy, and it takes a very little time (compared to galaxy-scale distances) to improve it to the point it's very weak. Humanity switched very quickly from weak radio signals (because the power sources were weak) to very weak radio signals (because we knew better what we were doing) to digital. That's a very short time frame and a weak signal. Not likely to be detected.
As for an intentional signal, well, if a powerful enough alien wants to be noticed, it will be. One could always come up with weird scenarios ("they want to test us so they're intentionally sending weak signals") but that's a very double edged sword ("they want to test us to see if they need to exterminate us") which doesn't justify SETI.