Cardassians arent inherently evil, nor are they inherently sneaky, its just thats the way they are portrayed because the majority of the ones which were featured were either soldiers or spies. It was in their training and perhaps in their up bringing - parents who act a certain way instil their ideals on their children and often they adopt that behaviour.
We did see examples of Cardassians who could be trusted, like the scientists who worked on the Wormhole communications project (other than the spy obviously) and Dukats daughter…these individuals had a different upbringing.
To say all Cardassians are evil is like to say all Bajorans are terrorists/freedom fighters (depending on which side you look at it) or Klingons are all bloodthirsty which has been shown not to be true.
That said Worf was right, whether it was his mistrust which ended up being coming true out of chance or that they would have started a war with or without the Dominion whether the Klingons invaded or not.