Is it safe, or intellectually honest, to assume that no ethereal objects or concepts exist?

Since each person has limited time to devote to developing their picture of the world, and cannot research every concept in depth, a person will always make generalisations based on what they have researched properly.

Science has established to a high degree of certainty that there is no luminiferous aether, and no metaphysical soul in the sense of Cartesian Dualism. I am calling such ideas as ‘ethereal objects’, since they have an airy feel to them, with no anchor in scientific proof. Other examples which are not yet rejected are Dark Matter/Energy, and the philosophical concept of Qualia, neither of which I personally believe to exist. I generally think of religious ideas in this group as well, although deist ‘uncaused cause’ deities are not strictly included. On a side note, is there an existing term to use instead of my ‘ethereal objects’?

So is it intellectually honest, or a reliable rule to follow, to remain sceptical of all propositions relying on ethereal objects until proven otherwise? Can you give me an example of such a concept that is either proven or widely accepted in academic circles?

I do not want this to turn into a purely religious discussion, or a defence of dualism. Please address the ideal of an ethereal object directly.