Last year I played dozens of Bonanza bonuses and found +5 to be a fairly reliable curse. Why? Because it usually lands on a drop after GOLD, or sometimes GOL where the D and +5 both drop at once.
Interesting stat: In my experience playing Bonanza, 80% of bonuses which hit off a tease were terrible or below average, whereas the opposite was true if GOLD smashed in entirely without a tease. The only bonus I ever had which breached 1000x came off GOLD +5 dropping in at once with no tease.
Coincidence? Maybe, maybe not. So I’ve heard, every bonus spin in Bonanza is random so you wouldn’t expect the trigger to tell you anything, but that doesn’t necessarily mean there aren’t other pre-determined parameters to a bonus and it’s only random within those.