I think being 'upfront and honest' includes a review of the damage that this disease has been associated with.
I see information parallels with this disease and the human disease of genital herpes. As a nurse I regularly get requests from people for information about this disease (as well as many others, part of what I do is give people information as well as referrals to free or low cost care so they can get medical follow up).
Many times herpes is not a big deal, in fact many people do not even know they have it because in many people it shows no symptoms.
But for some, their symptoms are painful and outbreaks frequent.
By far the most serious consequence is to neonates. If a mother has an outbreak at the time of childbirth and doctors are aware, there is frequently a Caesarean. If the mother has an outbreak and no one is aware, and the baby contracts the disease, there is a significant risk to the child of death, blindness, or permanent neurological damage.
This being so, those who know they have the disease should inform their prospective partners to the risk of acquiring it. It does not always happen that way, and I think that a refusal to share one's knowledge is extremely unethical.
I think that people have a right to make informed decisions and here, I think that if this disease is possibly widespread, that people who know about the disease should inform their purchasers of the possibilities of damage, pending further research.
It may be that in fact only certain strains of dragons get this or or that is it not as widespread as some people seem to think. But I do not think that waiting for the research results and meanwhile not educating one's customers is fair. It may not be a terrible disease. It may on the other hand be a devastating disease. It may, like herpes, be mild in most but devastating to some. Right now, we just are not certain but there does seem to be evidence linking it with damage.
Because of the potential damage being linked to the disease, I think the ethical path is to let one's customer be informed and let them decide.