I have several sites which have unique templates. I just launched a new site and uploaded one of my old templates and, without there being a stitch of text on page anywhere, Google knows what that template is associated with in terms of keywords.
So says the adsense block the template has. To test I switched templates and the adsense topic changes as well, it exactly matches what that template was used for before.
I assumed it was most likely because of an alt tag or theme title or a css file word or an adsense tracking term or SOMETHING on page but it's not, the theme is completely generic. I switch themes, adsense switches keywords to match what the theme was previously used for.
This is interesting to know, especially if you have a widely distributed template or have used the same theme on multiple topics.
