I don't think there's a one-size-fits-all solution for this. A simple way of determining whether your string IS in that case is to convert it TO that case and then check and see if the converted version is equal to the original. You can reference this article--
Letter Case Conversion Algorithms: Title Case, Toggle Case[
^]--which gives some code for title and toggle cases. You could also use the old VB6 StrConv method, which is still available (ProperCase is the same as TitleCase):
Dim s As String = "this is a test"
MessageBox.Show(StrConv(s, VbStrConv.ProperCase))
Note that proper/title case might not quite be what you might want. "A Tale of Two Cities" using the above title/proper case definitions gets you "A Tale Of Two Cities". I'd want that "Of" to be lowercase. A custom, character by character, solution is likely not that complex and will give you finer control of the results.