As a design decision we chose to make all 'bonuses' that had significant negative effects revealed by default, so players aren't spending resources to be penalized when the bonus the search revealed turns out to be harmful. It's already enough of a gamble to search for bonuses and risk not finding any.
We also made all gravity well radius altering bonuses revealed by default so that all players are equally affected by them. This is easily plausible from an in game perspective since all ships would have sensor systems for detecting a stellar body's gravitational pull, given that it is the main factor in determining phase jump exit distances.
