Avocado produces a dark honey with greenish tint. Avocado nectar contains a substantial fraction of a unique 7-carbon sugar, persitol. I don't believe honeybees can metabolize the sugar or have an enzyme to rearrange it. Avocado also have abundant phenolic compounds in the nectar (usually associated with dark honeys).
Avocado honey was rejected on a commercial scale, due to the USDA grading that favored water-white clover honey. It recently has been marketed as a special crop. It is less sweet than other honeys due to the persitol (which is not "tasted" as sweet on the tongue). The milder sweetness allows the other flavors to be recognized.
Bees are used to pollinate California Avocado -- (in the late spring bloom). Pollination requires well distributed hives, since bees will move off the trees if nearby wildflowers are present. In the past, the honey was held off the hive and used to stimulate (fed back) to splits for the melon pollination / citrus honey production following the Avocado bloom. Some is now being collected for the "boutique" market, helped by the intense marketing campaigning that Avocado's benefit from.
It should be recognized that Avocado evolved in the absence of honeybees, and the nectar composition was likely selected to attract a co-evolved Central American small stingless bees that could selectively use the unique sugar component
I believe some of the other unique honey's may be parallel to Avocado in dominance of unique sugars and co-evolution with a specialized pollinator. An extreme case might be Protea that are pollinated by rodents and have nectar consisting of 39% xylose -- completely undigestible to bees (and hence toxic), but easily broken down by the Namaqua rock mouse which is the pollinator.