I'm pretty sure almost never, the exception being serial gold sellers.
You are never able to tell if Jagex has flagged your IP. I recommend just change your IP frequently to prevent any bans.
How do you go about changing your IP?
Some IPs can be changed by unplugging your router then plugging it back in.
Some IPs can be changed by unplugging your router then plugging it back in.
Mine does, but it only changes slightly. Is that enough for a "fresh IP" ?

