Not sure if I'm correct on this one, but when you're just exploring around and suddenly trigger what seems like a random perception check (near traps or hidden objects for example), that is passive perception checks right? Cause those don't seem to be implemented correctly if they are. Passive perception checks are supposed to be...well, passive. They aren't a roll, they're a static number you have on your character sheet. If my passive perception is 17, then I beat any passive perception checks with a 17 or lower DC, anything higher than that I fail. It's that simple, my entire party shouldn't fail a passive perception check only to succeed on it if I save scum it and try again, because the outcome on it should always be the same.