I've never seen thigh-high boots worn over skinnies - interesting! I think my one comment would be that the outfit is a lot of form-fitting pieces. What would you think of mixing it up a bit? For example, if the jeans/boots combo peeked out from under a top that had a little more volume, it would be a bit of a surprise.
To address your question, I don't think over-the-knee boots read "trashy" in the way they did long ago, but I also think there are ways to make them more subtle and thus more elegant. I usually wear mine with skirts, and that way, it's not obvious that they're thigh-high boots. I didn't own such boots when I was working, but I think kk has a point - I would not have worn them to my job.