for planes i think it's not such of not being detected but more being detected the later possible . when stealth planes enter the game F-22 not included , some SEAD planes have already cleaned the place . i think stealth caracteristic for planes is a political choice , to minimize the chance of being it by a mobile SAM and to avoid having a pilot captured . for ships (don't know if it's the question) stealth is very efficient , i heard that large ships can have the signature of fishing vessels . concerning F-22 stealth caracteristic , i can't tell if the plane is undetectable as annouced , as the plane is still pretty secret