As written, unless you're behind a barrier or under a concealment power all the time of strength twice the force of a spirit someone is willing to summon you are as good as found.

I'm wondering what you or your players do about that to not have them get caught whenever somebody wants them.

Masks. Disguise skill. Physical Mask spell. If the conjurer doesn't know what you look like then the spirit can't search for you.

Well, just speaking of logistics, it takes time for the spirit to find the runner then report back. then by the time the searching party arrives, the runners might very well be gone. additionally, runner could be moving around using nanopaste disguises or something as well. I know my social adept has a melanin control and facial sculpt, i never look the same twice. I can switch it up whenever, whereever. I would definitely be doing that on a hourly basis if my group and I pissed off some powerful people.

With the new rules on the spirit master link reporting back isn't such an issue.

Also does the caster have to have seen your face or can they send a spirit after you if they've sighted your aura?

Though disguises would help a lot. I should hint more to my players to use those.

Yeah, I mean, you as a GM are always at liberty to make your characters role some sort of common sense check to see if they realize they very well could be hunted for whatever it is that they did. And that it might make sense to lie low for a while or at least disguise themselves if they must travel around. If their fake SINs got flashed, it might be wise to dump them and get new ones as well.

It's FM. It doesn't work in any fashion that is susceptible to that kind of manipulation. The spirit just gets a reduction for wards, even though there isn't any way it's going to go through the ward to search for stuff. It just knows the target is there. How, I have no idea. So you don't need much of a "mental image" per the book.

If you want to to work in a more logical way you have to rewrite the power completely. And wards would be a pretty much 100% showstopper then, as they should be.