Downvoting is a privilege given to users after reaching 125 reputation. The rationale is that at this point they know the system well enough to judge what makes a good question and what doesn't. There are no strict rules for when to vote how, just guidelines ("no research effort, unclear or not useful" is the mouseover on the downvote button). After all, we cannot make a rule for everything.
I just wondered if I was getting downvotes and close votes for (IMHO the entirely spurious) reason that surely that's not the right question.
I have absolutely no idea what you mean here, and I would wish you would stop asking this kind of hypothetical questions on meta. Either give a concrete example, or don't ask at all. This can be classified as 'not a real question'.
Is this a valid reason for the vote?
Per the above, everything that a 125-rep user deems valid, is valid.