There are a number of things that can affect crystallization; Storage conditions, filtering, what the bees foraged, etc.

There are some genuine honeys which rarely crystalize.

Afaik (as an amateur beekeeper), it is not a good indicator of anything in particular, there are even reports of adulterated honey crystallizing. This make sense, since honey and fake honey are both a supersaturated solution of sugars that will gladly crystalize if given an opportunity.