Not "dumb" at all save to the fool. If one can forge passports, currency, etc., you think it would be hard to forge a tax return?
Anyway, in 2006 was when Melania applied for citizenship. She, and Trump, filed jointly in 2005. In order for her to fill out her application she needed to provide evidence she had paid taxes for at least three years. That would have included 2005, and thus the claim made by Trump that the form was "illegally" released is just another of his long lists of lies.
The second problem Trump has is that in 2006 Trump sued author Timothy O'Brian for calling Trump a "millionaire" not "billionaire" in a book he had released in 2005. In order to prove his wealth Trump would have had to release his tax record thus making them part of the public record:
http://www.nationalreview.com/article/431575/donald-trump-tim-obrien-courtroom-story
But hey, that has to deal with reality, and not alternative facts to support ones pathological confirmation bias.
http://www.ctnewsjunkie.com/archives/entry/op-ed_and_the_winner_is_._._._confirmation_bias/
"Never in my lifetime have I witnessed more refusal on the part of the voters to check the facts, to scrutinize candidates’ statements, to accept reality as, well, reality.
“As much as we like to think that we use reason to evaluate evidence and come to conclusions, ‘It really goes back assward, a lot of times,’ said
Peter Ditto, a psychologist at University of California, Irvine. ‘People already have a firm opinion, and that shapes the way they process information.’ We hold beliefs about how the world works and tend to force new information to fit within these pre-existing narratives.
As Stan Bolander, a character on the 1990s TV show
“Homicide: Life on the Street” put it, “Nothing is real. There’s no reality. Take the color green — you see green, I see green. We call it green because this society has decided that this thing, this color, will be green. We think we have this shared experience of green, but who knows? Maybe my green is ‘greener’ than your green. Take color-blind people, for instance. They have to live with a stigma because what they see is not what we see as green. But maybe, just maybe, their perception is correct. They’re seeing pure green. They see true green"