Renblah, Welcome!
I believe that Viserys was the son of King Aerys II Targaryen and his queen (and wife and sister) Rhaella. The reason the Targs wed brother to sister was to keep the bloodlines pure. Since both Aerys and Rhaella were Targs, I see no reason for either of them to participate in a plot to introduce a non-Targ or half-Targ to the line of succession.
Not only was Viserys' hair correct, but his eyes were correct as well.
My guess is that somehow the Targs have some type of power to befriend dragons. It does not appear that Dany dreams like Bran and the Stark children do... but mayhaps I should reread ADWD. I don't think that all the Starks in every generation can do this, but somehow all of them in this generation can link minds and feelings with direwolves. The Targs may have the same power and mayhaps it is the dragons that make the power work differently. I think it is Dany's ability to bond with her dragons that allows her to withstand fire and heat.
In The Lord of the Rings, we see a few of the men of Middle-earth who have descended from the ancient Numenoreans... Aragorn, Denethor, Boromir, Faramir, and Imrahil are the best examples. The racial gifts/abilities of the Numenoreans reveal their Elven heritage. These abilities include prophecy, visions, long life, wisdom, superior health, courage, and social graces/nobility. Aragorn displays all of these qualities. So do Denethor and Faramir. Yet Boromir, Denethor's son and Faramir's brother, seems to lack prophecy and wisdom. Tolkien wrote something to the effect that "the blood of Numenor ran true in Denethor and Faramir, yet not in Boromir." Eomer told Aragorn something like, "Boromir is more like the sons of Eorl than the men of Gondor."
The hair and eyes mark the outward appearances of the noble houses of Westeros, but it is the more subtle, or hidden, qualities that denote the true heirs of Houses Targaryen, Stark, and Reed.
I'm also reminded of the biblical story of Jacob and Esau. The twin brothers fought over their father's gifts. Esau, as the elder brother, was to recieve the lion's share of the inheritance plus a spiritual blessing, i.e. a special prophecy. First, Jacob convinced Esau to sell him the larger inheritance of property and land. Later, Jacob successfully tricked his blind father, Isaac, to give him the prophecy of success and domination. Esau, while not concerned with losing his inheritance (he was going to be successful even without his father's money), flew into a murderous rage upon learning that Jacob stole his blessing and Jacob was forced to flee into exile for over a decade.
The point that I'd like to make is that the outward gifts of money, property, and land meant nothing to Esau. But the hidden and subtle blessing, the prophecy of God's good will, was the real sign of who would succeed Isaac... and Esau knew it had been stolen from him.
I'm not saying that the Targaryen ability to bond with dragons was up for grabs, I'm just saying Dany had it and Viserys did not... much to Viserys' disappointment.
Just my two cents.