I always do it to people who are obviously botting, like lately I've reported tons of people for using a fail master farmer thiever that misclicks to the stalls and doesn't run when the guard attacks. After reporting I usually wait a few mins and add the person to my friend list if they're high level or rich and every now and then check if they've been banned. People who bot on some +100cb accounts while they're afk deserve to get banned.
E: I've also noticed that people like to report skillers and high levels most, so I usually disguise my accounts as poor 25-50 cb's, that nobody pays attention to. For example, I've botted 55-83 fishing in f2p at karamja without seeing anyone directly to me more than once or twice asking for a fire.