Yes, masking will reduce your radar signiture, and if your not on their radar then they can't see you at all.

Once you lock them however, you're immediately visible. NPC and PVP works the same for this.

Helpful when hunting for artifacts, too bad there's no geo scanner bonus for assault bots

I'm at 2.3% on research for T4 Geo-scanner... should only be another 2 months *lol*

Masking and sheilds, and ECCM to break the demob will get you out of all but the most persistent (observer) situations.

The termis acutally makes a great scan bot, good accumulator for sheilds and masker, with a larger cargo. A t4 frame on an empty Term is over 80 Kph with nav 10, and the geo bonus if you can't get the T4 scanner. However, it is visible at 1k, even masked it's not great for sneaking, but I open infestations and GO's all the time - as long as you have a sheild and T4 lwf you can get away from most any cache spawn. Scan, double click cache in landmarks, 'v'/'g' - autorun - keep running - then run some more.

I made the mistake of loading up a termis with t4 shield and hardeners and ignoring mobs, RIP sweet Termis, but that was before ECCM broke demob, so it maybe it would work now;

Edit: It the cache is 400m off a npc spawn you can get in and out with the Termis at speed (non-mechs), although the assault could probably get you to caches 250m away, i'm not sure the 150m trade off would be worth using the assualt. And caches will reset the next day, so you can just skip those.