You know, I still read it that both arrested and/or convicted would have to be for a crime involving moral turpitude. On other questions they use a semicolon where they want to put a harder break.

So if they wanted to include arrests (for any crime) plus convictions for crimes involving moral turpitude, wouldn't they have written:

Have you ever been arrested; or convicted for an offense or crime involving moral turpitude.

In fact, while typing that I now believe even more that the or links rather than excludes. Take the last bit of the phrase: for an offense or crime involving moral turpitude. If the or was excluding you could read this as:
Have you ever been arrested for an offense?

A moral turpitude offense is a subset of all the offenses so if the or's were excluding or's (or whatever the correct phrase is) there wouldn't be a need to mention moral turpitude at all.

Given that you likely aren't arrested for doing nothing they could reduce the question to a much more readable:
Have you ever been arrested?

So all that said, for what it's worth, IMHO, usual disclaimers apply, I read this that if one has been arrested and/or convicted for a crime that does not involve moral turpitude, you can tick No and travel under the VWP.

One does wonder if the ambiguity is there by accident, or intentionally?