Hey David.
It's a very valid question - and a problem that I've personally taken exception to as well...
The Terms and Privacy SKO's (Skin Objects) use your homepage skin (sans other modules) - this is not good. The other issue that our team has found from an SEO perspective, is that search engines index and, worse still, give weighting to these pages. The tack we've taken (and it works well) is NOT TO USE these SKO's and rather create actual pages for Terms of Use and Privacy Policy pages...
Obviously, DNN doesn't like it when you name the pages the same at top level, so we usually put these as hidden child-links of "about us" like so:
www.domain.com//AboutUs/TermsofUse.aspx and /AboutUs/PrivacyPolicy.aspx
Semantically, this makes sense as the content is "about" the company's policies and terms of use... Also, this way of doing things also allows out clients to easily edit the Terms of Use and Privacy Policy by way of simple Text / HTML modules (and not via localization and language options through admin). Lastly, doing it this way also obviously allows us to create and apply a specific skin for those pages.
We then put in manual links to these tabs / items in our .ASCX skin files like so:
<a href="http://<%= PortalSettings.PortalAlias.HTTPAlias%>/AboutUs/TermsofUse.aspx">Website Terms of Use</a> | <a href="http://<%= PortalSettings.PortalAlias.HTTPAlias%>/AboutUs/PrivacyPolicy.aspx">Privacy Policy</a>
Lastly, when we create these pages, we apply a "do not follow" to our robots.txt file in the site's root - telling search engines not to index these pages. Magic.
I don't know relevant this option is for you, but our team (some of the best in the biz) swear by this.
Jon