Successful scan probe allows you to warp directly to someone, and most people who use them are in ships that can cloak, so they can warp to you while cloaked and you wouldnt even know. They then get their entire gang to warp to you.
So the BEST of the best safespots are either made previous to the Exodus expansion. Previous to it, you could warp book mark a system, then in another system try to "warp to" it and go around over 1000 AU away. thats pretty much impossible to scan for, however it is an exploit and receives a ban if caught.
Best possible safe spot creatable now is with the "Observer deep space probe I", In a previous post I said discovery probe, but I was inncorrect in probe names

. Observer probe throws you pretty much at a random spot within like 120 AU. And if you are off the systems x axis by at least 1 au, you cannot be probed for. And Observer Probes can find you but they are incredibly inacurate.