the Sun and Star, but also the court cards or say the 10 of cups/ace cards
It's more than just negative/positive, it's an entire spectrum for each card. From negative to positive and positive to negative. So, you could say there's also a gray area there for each card. Not absolutely positive nor absolutely negative--a little of both.
The Sun: you've never been sunburned?
Too much sun isn't always good for you. And you'd get really annoyed by someone who always greeting your sad stories with: "look on the bright side!" Likewise with someone always rational when you wanted to be fanciful, or someone relentlessly logical when you wanted to be emotional. The Sun shines wakes you up and makes dreams go away. Good if you're having a nightmare. Not so good if you're in the middle of a really wonderful fantasy.
The Star: The Star is often seen as cold and distant. It offers hope and healing in the now, but that future is a ways off. That's the trick of the Star. This future can come true...but only eventually and if you stay on the path. You could easily get tired, discouraged, bored, or give up. And you might well think: "Thanks for nothing!" in regards to the Star. It was hope, but a distant hope. You might wish you hadn't been offered it at all.
10/Cups: this card promises you emotional happiness that you want to pass on to others, but not financial security. Or health. Or passion. Or success. Or fame. Great if your dream is to have a big family with lots of kids and so you can share all that, and who cares if you're poor, in bad health, and obscure. But if you want any of that other stuff...this might not be happily ever after.
Ace/Cups: All Aces are energy without direction and so are in those "gray" areas. Circumstance determines how positive or negative they are. For someone who hasn't been feeling anything, Ace/Cups (a wellspring of feeling) is good. For someone who feels too much already, not so good; this is one more gusher with no direction, and they're already drowning in water that isn't going anywhere. So, negative.
As for Court cards...why is it that you can't see them as negative? You can't see the King/Pents as someone who might only care for money and finances, not people? Or the Knight/Wands as hot tempered and impatient, trampling others in his race to win?