My personal opinion is that this is exactly the effect Aleister Crowley, the creator of this deck, intended. He was a clever man, and without a doubt had a certain ruthlessness. He worked very hard to evoke an aura of mysterious, powerful evil aroound himself - probably as a rebellion against the Christian morality he grew up with. Artists have often rebelled visibly against the standards they were raised with because they found them limiting, and in that sense, Crowly created his life as artwork. I'm quite sure that he was an unpleasant person in many respects but many great artists were the same; it's a question of ego and power and feeling of a mission. (Let's not even begin to think about rulers and politicians! How many of our laws were created by people we wouldn't like to drink a cup of tea with.)
His philosophy of life reminds me of Nietzsche who als rebelled strongly against the Christian teachings. They share an emphatic vision of the assertion of the Will.
I don't think that this carefully created evil reputation of Crowley's contaminates his deck. The Thoth is in many ways a very intellectual work of art. It evokes and sums up centuries of Western esoteric teachings and makes them approachable, even "useful" for people who are not schooled in it. Crowley doesn't hide these secrets behind a harmless-looking narrative veil, they're there to see for everyone in the Thoth. At the same time, the minors of the Thoth remain often very faithful to the compositions of the Tarot de Marseille tradition.
There are so many influences here that are not Crowley. And the touches he added, like the word Thelema on the hilt of the Sword in the Ace of Swords, ore the seal of the beast etc are well-thought out - and you can take them or leave them. Some won't even notice them. If people do and they're repelled by the Thelemic underpinnings of the Thoth because Thelema is a rejection of many Christian principles, then they're free to do so. But looking at the Thelemic principles, well, they're quite compatible with many other world views that celebrate life, change, joy and individual willpower.
It's totally possible to use the Thoth without subscribing to the philosophy and/or spiritual practice of Thelema. I think the overwhelming majority of Thoth users don't.
Then, there is the personality of Frieda Harris. (She was not the daughter of a peer and as far as i know shouldn't be called Lady Frieda Harris - as wife of a baronet, her proper title is Lady Harris. Checked it - true.) She was a wonderful artist, and the correspondence between Crowley and Harris is very interesting to read. She follows his direction but there is a distance to his theoretical writings that she expresses with modesty and humour.
(The letters also show the many prejudices Crowley had and a tendency to nasty, judgmental gossip - but also a brilliant creative head, and often writing like in shorthand, probably relating to discussions they had when they met.)In reference to your books–I suppose you know that most of them would be easier for a Beginner written in Sanscrit & that anyone reading them would go off their heads. Therefore the Wise (“like myself”) take them in snappy bits & only when they are feeling strong.
Without the great talent and intelligence of Harris, the Thoth deck would look totally different. Her use of projective geometry, her interpretation of the colour scales and the whole concept, are such an important part of the deck, it's impossible to decide who influences us more strongly when we read with the deck, Crowley or Harris.
And then there is the energy and willpower of the reader him/herself. Our intentions, our beliefs.
Crowley's energy is only ONE, albeit a very important, aspect of the Thoth. There is the tarot tradition, esoteric teachings, mythological material, Harris' influence and creativity - it all plays together.
I bought my first Thoth without knowing anything about Crowley and I've been using it for more than 20 years. Its "voice" as a deck (allow me this anthropomorphism) is wise, all-knowing and empowering. Readings are serious, to the point and always bring a new angle that I didn't think about before. The popularity of the Thoth is based on its pure brilliance as a reading deck.
It works for intuitive readings, for readings for other people, for esoteric study, for meditation and scrying and dream work... I didn't try it for shadow work but I'm sure it would be wonderful for that, too.
I think a work of art always transcends its creator. Crowley's carefully crafted reputation as powerful evil man is one thing, his deck another. You can't de-Crowleyfy the Thoth but in my opinion, his best, most serious powers of mind went into the making of the deck.
Try it for yourself. A tarot deck is just a pack of colourful pieces of cardboard, like an art postcard. You don't ask yourself whether Gauguin was a very nice guy when you put up a poster of his artwork on your wall. The question is what the work of art does for you.
For me and many others, the Thoth is a tool that helps us to recognize the patterns of our lives without sugarcoating, without flattery, just a totally honest voice.