"Dressing down" to impress in academic settings
If an academic is dressed in an unusually casual manner, I generally ignore it.

If an academic is dressed in an unusually formal manner, I assume one of these:


They are an administrator, or manager, rather than an academic
They are here for a job interview and they don't know it is not necessary to dress formally
They are going to an event outside academia, like a funeral


I do not think anyone is impressed by either dressing up or down, but it can send a signal.