Learn English – Can the word “exposure” be used to mean something positive

It depends significantly on the context.

In terms of ADD and ADHD, the fact that they are abbreviations generally removes any connotation that disorder may hold because ADD and ADHD are very common terms that people have tended to directly associate with the condition in question.

If, however, disorder were to be spelled out in terms of a clinical diagnosis, there might be a small negative connotation, but generally speaking, I do not think it would be very significant.

On the other hand, if you were to say he has a mental disorder, that is very negative and might well be considered to be bordering on rude.

It really depends on the context, and because of that, I think you would be best to say neutral. For example, here are three cases:

Positive: My friend brought an expensive wine to the party for us to try.

Neutral: The electric dryer was more expensive than the gas.

Negative: I was shocked by how expensive hotel rooms were because of the convention.

I would say that in general most English speakers would say something being "expensive" is a bad thing, but actual usage is rarely that simple. Ultimately, the connotation depends on who is paying the "expensive" price.